bdlcc_queue.h

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/// @file bdlcc_queue.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlcc_queue.h                                                      -*-C++-*-
#ifndef INCLUDED_BDLCC_QUEUE
#define INCLUDED_BDLCC_QUEUE
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlcc_queue bdlcc_queue
/// @brief <span style="color: var(--deprecated-color-dark)">DEPRECATED:</span>  Provide a thread-enabled queue of items of parameterized `TYPE`.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlcc
/// @{
/// @addtogroup bdlcc_queue
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlcc_queue-purpose"> Purpose</a>
/// * <a href="#bdlcc_queue-classes"> Classes </a>
/// * <a href="#bdlcc_queue-description"> Description </a>
///   * <a href="#bdlcc_queue-thread-enabled-idioms-in-the-bdlcc-queue-interface"> Thread-Enabled Idioms in the bdlcc::Queue Interface </a>
///   * <a href="#bdlcc_queue-use-of-the-bdlc-queue-interface"> Use of the bdlc::Queue Interface </a>
///   * <a href="#bdlcc_queue-warning-synchronization-required-on-destruction"> WARNING: Synchronization Required on Destruction </a>
///   * <a href="#bdlcc_queue-usage"> Usage </a>
///     * <a href="#bdlcc_queue-example-1-simple-thread-pool"> Example 1: Simple Thread Pool </a>
///     * <a href="#bdlcc_queue-example-2-multi-threaded-observer"> Example 2: Multi-Threaded Observer </a>
///
/// # Purpose {#bdlcc_queue-purpose}
/// Provide a thread-enabled queue of items of parameterized `TYPE`.
///
/// # Classes {#bdlcc_queue-classes}
///
/// -   bdlcc::Queue: thread-enabled `bdlc::Queue` wrapper
///
/// @see  bdlc_queue
///
/// @deprecated  use `bdlcc::Deque` instead.
///
/// # Description {#bdlcc_queue-description}
/// This component provides a thread-enabled implementation of an
/// efficient, in-place, indexable, double-ended queue of parameterized `TYPE`
/// values, namely the `bdlcc::Queue<TYPE>` container.  `bdlcc::Queue` is
/// effectively a thread-enabled handle for `bdlc::Queue`, whose interface is
/// also made available through `bdlcc::Queue`.
///
/// ## Thread-Enabled Idioms in the bdlcc::Queue Interface {#bdlcc_queue-thread-enabled-idioms-in-the-bdlcc-queue-interface}
///
///
/// The thread-enabled `bdlcc::Queue` is similar to `bdlc::Queue` in many
/// regards, but there are several differences in method behavior and signature
/// that arise due to the thread-enabled nature of the queue and its anticipated
/// usage pattern.  Most notably, the `popFront` and `popBack` methods return a
/// `TYPE` object *by* *value*, rather than returning `void`, as `bdlc::Queue`
/// does.  Moreover, if a queue object is empty, `popFront` and `popBack` will
/// block indefinitely until an item is added to the queue.
///
/// As a corollary to this behavior choice, `bdlcc::Queue` also provides
/// `timedPopFront` and `timedPopBack` methods.  These methods wait until a
/// specified timeout expires if the queue is empty, returning an item if one
/// becomes available before the specified timeout; otherwise, they return a
/// non-zero value to indicate that the specified timeout expired before an item
/// was available.  Note that *all* timeouts are expressed as values of type
/// `bsls::TimeInterval` that represent **ABSOLUTE** times from 00:00:00 UTC,
/// January 1, 1970.
///
/// The behavior of the `push` methods differs in a similar manner.
/// `bdlcc::Queue` supports the notion of a suggested maximum queue size, called
/// the "high-water mark", a value supplied at construction.  The `pushFront`
/// and `pushBack` methods will block indefinitely if the queue contains (at
/// least) the high-water mark number of items, until the number of items falls
/// below the high-water mark.  The `timedPushFront` and `timedPushBack` are
/// provided to limit the duration of blocking; note, however, that these
/// methods can fail to add an item to the queue.  For this reason,
/// `bdlcc::Queue` also provides a `forcePushFront` method that will override
/// the high-water mark, if needed, in order to succeed without blocking.  Note
/// that this design decision makes the high-water mark concept a suggestion and
/// not an invariant.
///
/// ## Use of the bdlc::Queue Interface {#bdlcc_queue-use-of-the-bdlc-queue-interface}
///
///
/// Class `bdlcc::Queue` provides access to an underlying `bdlc::Queue`, so
/// clients of `bdlcc::Queue` have full access to the interface behavior of
/// `bdlc::Queue` to inspect and modify the `bdlcc::Queue`.
///
/// Member function `bdlcc::Queue::queue()` provides *direct* modifiable access
/// to the `bdlc::Queue` object used in the implementation.  Member functions
/// `bdlcc::Queue::mutex()`, `bdlcc::Queue::notEmptyCondition()`, and
/// `bdlcc::Queue::notFullCondition()` correspondingly provide *direct*
/// modifiable access to the underlying `bslmt::Mutex` and `bslmt::Condition`
/// objects respectively.  These underlying objects are used within
/// `bdlcc::Queue` to manage concurrent access to the queue.  Clients may use
/// these member variables together if needed.
///
/// Whenever accessing the `bdlcc` queue directly, clients must be sure to lock
/// and unlock the mutex or to signal or broadcast on the condition variable as
/// appropriate.  For example, a client might use the underlying queue and mutex
/// as follows:
/// @code
///    bdlcc::Queue<myData>  myWorkQueue;
///    bdlc::Queue<myData>& rawQueue = myWorkQueue.queue();
///    bslmt::Mutex&        queueMutex = myWorkQueue.mutex();
///        // other code omitted...
///
///    myData  data1;
///    myData  data2;
///    bool pairFoundFlag = 0;
///    // Take two items from the queue atomically, if available.
///
///    queueMutex.lock();
///    if (rawQueue.length() >= 2) {
///        data1 = rawQueue.front();
///        rawQueue.popFront();
///        data2 = rawQueue.front();
///        rawQueue.popFront();
///        pairFound = 1;
///    }
///    queueMutex.unlock();
///
///    if (pairFoundFlag) {
///        // Process the pair
///    }
/// @endcode
/// Note that a future version of this component will provide access to a
/// thread-safe "smart pointer" that will manage the `bdlc::Queue` with respect
/// to locking and signaling.  At that time, direct access to the `bdlc::Queue`
/// will be deprecated.  In the meanwhile, the user should be careful to use the
/// `bdlc::Queue` and the synchronization objects properly.
///
/// ## WARNING: Synchronization Required on Destruction {#bdlcc_queue-warning-synchronization-required-on-destruction}
///
///
/// The behavior for the destructor is undefined unless all access or
/// modification of the object is completed prior to its destruction.  Some form
/// of synchronization, external to the component, is required to ensure the
/// precondition on the destructor is met.  For example, if two (or more)
/// threads are manipulating a queue, it is *not* safe to anticipate the number
/// of elements added to the queue, and destroy that queue immediately after the
/// last element is popped (without additional synchronization) because one of
/// the corresponding push functions may not have completed (push may, for
/// instance, signal waiting threads after the element is considered added to
/// the queue).
///
/// ## Usage {#bdlcc_queue-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Simple Thread Pool {#bdlcc_queue-example-1-simple-thread-pool}
///
///
/// The following example demonstrates a typical usage of a `bdlcc::Queue`.
///
/// This `bdlcc::Queue` is used to communicate between a single "producer"
/// thread and multiple "consumer" threads.  The "producer" will push work
/// requests onto the queue, and each "consumer" will iteratively take a work
/// request from the queue and service the request.  This example shows a
/// partial, simplified implementation of the `bdlmt::ThreadPool` class.  See
/// component @ref bdlmt_threadpool  for more information.
///
/// We begin our example with some utility classes that define a simple "work
/// item":
/// @code
/// enum {
///     k_MAX_CONSUMER_THREADS = 10
/// };
///
/// struct my_WorkData {
///     // Work data...
/// };
///
/// struct my_WorkRequest {
///     enum RequestType {
///         e_WORK = 1,
///         e_STOP = 2
///     };
///
///     RequestType d_type;
///     my_WorkData d_data;
///     // Work data...
/// };
/// @endcode
/// Next, we provide a simple function to service an individual work item.  The
/// details are unimportant for this example.
/// @code
/// void myDoWork(my_WorkData& data)
/// {
///     // do some stuff...
///     (void)data;
/// }
/// @endcode
/// The `myConsumer` function will pop items off the queue and process them.  As
/// discussed above, note that the call to `queue->popFront()` will block until
/// there is an item available on the queue.  This function will be executed in
/// multiple threads, so that each thread waits in `queue->popFront()`, and
/// `bdlcc::Queue` guarantees that each thread gets a unique item from the
/// queue.
/// @code
/// void myConsumer(bdlcc::Queue<my_WorkRequest> *queue)
/// {
///     while (1) {
///         // 'popFront()' will wait for a 'my_WorkRequest' until available.
///
///         my_WorkRequest item = queue->popFront();
///         if (item.d_type == my_WorkRequest::e_STOP) break;
///         myDoWork(item.d_data);
///     }
/// }
/// @endcode
/// The function below is a callback for `bslmt::ThreadUtil`, which requires a
/// "C" signature.  `bslmt::ThreadUtil::create()` expects a pointer to this
/// function, and provides that function pointer to the newly created thread.
/// The new thread then executes this function.
///
/// Since `bslmt::ThreadUtil::create()` uses the familiar "C" convention of
/// passing a `void` pointer, our function simply casts that pointer to our
/// required type (`bdlcc::Queue<my_WorkRequest*> *`), and then delegates to the
/// queue-specific function `myConsumer`, above.
/// @code
/// extern "C" void *myConsumerThread(void *queuePtr)
/// {
///     myConsumer ((bdlcc::Queue<my_WorkRequest> *)queuePtr);
///     return queuePtr;
/// }
/// @endcode
/// In this simple example, the `myProducer` function serves multiple roles: it
/// creates the `bdlcc::Queue`, starts out the consumer threads, and then
/// produces and queues work items.  When work requests are exhausted, this
/// function queues one `STOP` item for each consumer queue.
///
/// When each Consumer thread reads a `STOP`, it terminates its thread-handling
/// function.  Note that, although the producer cannot control which thread
/// `pop`s a particular work item, it can rely on the knowledge that each
/// Consumer thread will read a single `STOP` item and then terminate.
///
/// Finally, the `myProducer` function "joins" each Consumer thread, which
/// ensures that the thread itself will terminate correctly; see the
/// @ref bslmt_threadutil  component for details.
/// @code
/// void myProducer(int numThreads)
/// {
///     my_WorkRequest item;
///     my_WorkData    workData;
///
///     bdlcc::Queue<my_WorkRequest> queue;
///
///     assert(0 < numThreads && numThreads <= k_MAX_CONSUMER_THREADS);
///     bslmt::ThreadUtil::Handle consumerHandles[k_MAX_CONSUMER_THREADS];
///
///     for (int i = 0; i < numThreads; ++i) {
///         bslmt::ThreadUtil::create(&consumerHandles[i],
///                                   myConsumerThread,
///                                   &queue);
///     }
///
///     while (!getWorkData(&workData)) {
///         item.d_type = my_WorkRequest::e_WORK;
///         item.d_data = workData;
///         queue.pushBack(item);
///     }
///
///     for (int i = 0; i < numThreads; ++i) {
///         item.d_type = my_WorkRequest::e_STOP;
///         queue.pushBack(item);
///     }
///
///     for (int i = 0; i < numThreads; ++i) {
///         bslmt::ThreadUtil::join(consumerHandles[i]);
///     }
/// }
/// @endcode
///
/// ### Example 2: Multi-Threaded Observer {#bdlcc_queue-example-2-multi-threaded-observer}
///
///
/// The previous example shows a simple mechanism for distributing work requests
/// over multiple threads.  This approach works well for large tasks that can be
/// decomposed into discrete, independent tasks that can benefit from parallel
/// execution.  Note also that the various threads are synchronized only at the
/// end of execution, when the Producer "joins" the various consumer threads.
///
/// The simple strategy used in the first example works well for tasks that
/// share no state, and are completely independent of one another.  For
/// instance, a web server might use a similar strategy to distribute http
/// requests across multiple worker threads.
///
/// In more complicated examples, it is often necessary or desirable to
/// synchronize the separate tasks during execution.  The second example below
/// shows a single "Observer" mechanism that receives event notification from
/// the various worker threads.
///
/// We first create a simple `my_Event` data type.  Worker threads will use this
/// data type to report information about their work.  In our example, we will
/// report the "worker Id", the event number, and some arbitrary text.
///
/// As with the previous example, class `my_Event` also contains an `EventType`,
/// which is an enumeration which that indicates whether the worker has
/// completed all work.  The "Observer" will use this enumerated value to note
/// when a Worker thread has completed its work.
/// @code
/// enum {
///     k_MAX_CONSUMER_THREADS = 10,
///     k_MAX_EVENT_TEXT       = 80
/// };
///
/// struct my_Event {
///     enum EventType {
///         e_IN_PROGRESS   = 1,
///         e_TASK_COMPLETE = 2
///     };
///
///     EventType d_type;
///     int       d_workerId;
///     int       d_eventNumber;
///     char      d_eventText[k_MAX_EVENT_TEXT];
/// };
/// @endcode
/// As noted in the previous example, `bslmt::ThreadUtil::create()` spawns a new
/// thread, which invokes a simple "C" function taking a `void` pointer.  In the
/// previous example, we simply converted that `void` pointer into a pointer to
/// the parameterized `bdlcc::Queue<TYPE>` object.
///
/// In this example, we want to pass an additional data item.  Each worker
/// thread is initialized with a unique integer value ("worker Id") that
/// identifies that thread.  We create a simple data structure that contains
/// both of these values:
/// @code
/// struct my_WorkerData {
///     int                     d_workerId;
///     bdlcc::Queue<my_Event> *d_queue_p;
/// };
/// @endcode
/// Function `myWorker` simulates a working thread by enqueuing multiple
/// `my_Event` events during execution.  In a normal application, each
/// `my_Event` structure would likely contain different textual information; for
/// the sake of simplicity, our loop uses a constant value for the text field.
/// @code
/// void myWorker(int workerId, bdlcc::Queue<my_Event> *queue)
/// {
///     const int NEVENTS = 5;
///     int evnum;
///
///     for (evnum = 0; evnum < NEVENTS; ++evnum) {
///         my_Event ev = {
///             my_Event::e_IN_PROGRESS,
///             workerId,
///             evnum,
///             "In-Progress Event"
///         };
///         queue->pushBack(ev);
///     }
///
///     my_Event ev = {
///         my_Event::e_TASK_COMPLETE,
///         workerId,
///         evnum,
///         "Task Complete"
///     };
///     queue->pushBack(ev);
/// }
/// @endcode
/// The callback function invoked by `bslmt::ThreadUtil::create()` takes the
/// traditional `void` pointer.  The expected data is the composite structure
/// `my_WorkerData`.  The callback function casts the `void` pointer to the
/// application-specific data type and then uses the referenced object to
/// construct a call to the `myWorker` function.
/// @code
/// extern "C" void *myWorkerThread(void *v_worker_p)
/// {
///     my_WorkerData *worker_p = (my_WorkerData *) v_worker_p;
///     myWorker(worker_p->d_workerId, worker_p->d_queue_p);
///     return v_worker_p;
/// }
/// @endcode
/// For the sake of simplicity, we will implement the Observer behavior in the
/// main thread.  The `void` function `myObserver` starts out multiple threads
/// running the `myWorker` function, reads `my_Event`s from the queue, and logs
/// all messages in the order of arrival.
///
/// As each `myWorker` thread terminates, it sends a `e_TASK_COMPLETE` event.
/// Upon receiving this event, the `myObserver` function uses the `d_workerId`
/// to find the relevant thread, and then "joins" that thread.
///
/// The `myObserver` function determines when all tasks have completed simply by
/// counting the number of `e_TASK_COMPLETE` messages received.
/// @code
/// void myObserver()
/// {
///     const int NTHREADS = 10;
///     bdlcc::Queue<my_Event> queue;
///
///     assert(NTHREADS > 0 && NTHREADS <= k_MAX_CONSUMER_THREADS);
///     bslmt::ThreadUtil::Handle workerHandles[k_MAX_CONSUMER_THREADS];
///
///     my_WorkerData workerData;
///     workerData.d_queue_p = &queue;
///     for (int i = 0; i < NTHREADS; ++i) {
///         workerData.d_workerId = i;
///         bslmt::ThreadUtil::create(&workerHandles[i],
///                                   myWorkerThread,
///                                   &workerData);
///     }
///     int nStop = 0;
///     while (nStop < NTHREADS) {
///         my_Event ev = queue.popFront();
///         bsl::cout << "[" << ev.d_workerId    << "] "
///                          << ev.d_eventNumber << ". "
///                          << ev.d_eventText   << bsl::endl;
///         if (my_Event::e_TASK_COMPLETE == ev.d_type) {
///             ++nStop;
///             bslmt::ThreadUtil::join(workerHandles[ev.d_workerId]);
///         }
///     }
/// }
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlcc
 * @{
 */
/** @addtogroup bdlcc_queue
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bdlc_queue.h>
 
#include <bslma_allocator.h>
#include <bslma_usesbslmaallocator.h>
 
#include <bslmf_nestedtraitdeclaration.h>
 
#include <bslmt_condition.h>
#include <bslmt_lockguard.h>
#include <bslmt_mutex.h>
#include <bslmt_threadutil.h>
 
#include <bslmf_movableref.h>
 
#include <bsls_libraryfeatures.h>
#include <bsls_timeinterval.h>
 
#include <bsl_vector.h>
 
#include <vector>
 
 
namespace bdlcc {
 
                                // ===========
                                // class Queue
                                // ===========
 
/// This class provides a thread-enabled implementation of an efficient,
/// in-place, indexable, double-ended queue of parameterized `TYPE` values.
/// Very efficient access to the underlying `bdlc::Queue` object is provided,
/// as well as to a `bslmt::Mutex` and a `bslmt::Condition` variable, to facilitate thread-safe use of the `bdlc::Queue`.  
/// 
/// \note Note that   `Queue` is not
/// a value-semantic type, but the underlying `bdlc::Queue` is.  In this
/// regard, `Queue` is a thread-enabled handle for a `bdlc::Queue`.
///
/// See @ref bdlcc_queue 
template <class TYPE>
class Queue {
 
    // PRIVATE TYPES
    typedef typename bdlc::Queue<TYPE>::InitialCapacity QueueCapacity;
                                           // We need this typedef to work
                                           // around a bug in Sun WorkShop 6
                                           // update 1: if the typedef is
                                           // replaced by its actual definition
                                           // in the two constructors
                                           // initialization list, the compiler
                                           // erroneously reports a syntax
                                           // error ("Expected an expression").
 
    template <class VECTOR>
    struct IsVector;
 
    // DATA
    mutable
    bslmt::Mutex      d_mutex;             // mutex object used to synchronize
                                           // access to this queue
 
    bslmt::Condition  d_notEmptyCondition; // condition variable used to signal
                                           // that new data is available in the
                                           // queue
 
    bslmt::Condition  d_notFullCondition;  // condition variable used to signal
                                           // when there is room available to
                                           // add new data to the queue
 
    bdlc::Queue<TYPE> d_queue;             // the queue, with allocator as last
                                           // data member
 
    const int         d_highWaterMark;     // positive maximum number of items
                                           // that can be queued before
                                           // insertions will be blocked, or
                                           // -1 if unlimited
 
  private:
    // NOT IMPLEMENTED
    Queue(const Queue<TYPE>&);
    Queue<TYPE>& operator=(const Queue<TYPE>&);
 
    // PRIVATE MANIPULATORS
 
    /// Remove all the items in this queue.  If the optionally specified
    /// `buffer` is not 0, load into `buffer` a copy of the items removed in
    /// front to back order of the queue prior to `removeAll`.
    template <class VECTOR>
    void removeAllImp(VECTOR *buffer = 0);
 
    /// Remove up to the specified `maxNumItems` from the front of this
    /// queue.  Optionally specify a `buffer` into which the items removed
    /// from the queue are loaded.  If `buffer` is non-null, the removed
    /// items are appended to it as if by repeated application of
    /// `buffer->push_back(popFront())` while the queue is not empty and
    /// `maxNumItems` have not yet been removed.  
    /// 
    /// \pre The behavior is undefined   unless `maxNumItems >= 0`.  This method never blocks.
    template <class VECTOR>
    void tryPopFrontImp(int maxNumItems, VECTOR *buffer);
 
    /// Remove up to the specified `maxNumItems` from the back of this
    /// queue.  Optionally specify a `buffer` into which the items removed
    /// from the queue are loaded.  If `buffer` is non-null, the removed
    /// items are appended to it as if by repeated application of
    /// `buffer->push_back(popBack())` while the queue is not empty and
    /// `maxNumItems` have not yet been removed.  This method never blocks. 
    /// 
    /// \pre The behavior is undefined   unless `maxNumItems >= 0`.  
    /// \note Note that  the
    /// ordering of the items in `*buffer` after the call is the reverse of
    /// the ordering they had in the queue.
    template <class VECTOR>
    void tryPopBackImp(int maxNumItems, VECTOR *buffer);
 
  public:
    // TRAITS
    BSLMF_NESTED_TRAIT_DECLARATION(Queue, bslma::UsesBslmaAllocator);
 
    // TYPES
 
    /// Enable uniform use of an optional integral constructor argument to
    /// specify the initial internal capacity (in items).  For example,
    /// @code
    ///  const Queue<int>::InitialCapacity NUM_ITEMS(8));
    ///  Queue<int> x(NUM_ITEMS);
    /// @endcode
    /// defines an instance `x` with an initial capacity of 8 items, but
    /// with a logical length of 0 items.
    ///
    /// See @ref bdlcc_queue 
    struct InitialCapacity {
 
        // DATA
        unsigned int d_i;
 
        // CREATORS
 
        /// Create an object with the specified value `i`.
        explicit InitialCapacity(int i)
        : d_i(i)
        {}
    };
 
    // CREATORS
 
    /// Create a queue of objects of parameterized `TYPE`.  Optionally
    /// specify a `basicAllocator` used to supply memory.  If
    /// `basicAllocator` is 0, the currently installed default allocator is
    /// used.
    explicit
    Queue(bslma::Allocator *basicAllocator = 0);
 
    /// Create a queue of objects of parameterized `TYPE` having either the
    /// specified `highWaterMark` suggested maximum length if
    /// `highWaterMark` is positive, or no maximum length if `highWaterMark`
    /// is negative.  Optionally specify a `basicAllocator` used to supply
    /// memory.  If `basicAllocator` is 0, the currently installed default allocator is used.  
    /// 
    /// \pre The behavior is undefined   unless
    /// `highWaterMark != 0`.
    explicit
    Queue(int highWaterMark, bslma::Allocator *basicAllocator = 0);
 
    /// Create a queue of objects of parameterized `TYPE` with sufficient
    /// initial capacity to accommodate up to the specified `numItems`
    /// values without subsequent reallocation.  Optionally specify a
    /// `basicAllocator` used to supply memory.  If `basicAllocator` is 0,
    /// the currently installed default allocator is used.
    explicit
    Queue(const InitialCapacity&  numItems,
          bslma::Allocator       *basicAllocator = 0);
 
    /// Create a queue of objects of parameterized `TYPE` with sufficient
    /// initial capacity to accommodate up to the specified `numItems`
    /// values without subsequent reallocation and having either the
    /// specified `highWaterMark` suggested maximum length if
    /// `highWaterMark` is positive, or no maximum length if `highWaterMark`
    /// is negative.  Optionally specify a `basicAllocator` used to supply
    /// memory.  If `basicAllocator` is 0, the currently installed default allocator is used.  
    /// 
    /// \pre The behavior is undefined   unless
    /// `highWaterMark != 0`.
    Queue(const InitialCapacity&  numItems,
          int                     highWaterMark,
          bslma::Allocator       *basicAllocator = 0);
 
    /// Create a queue of objects of parameterized `TYPE` containing the
    /// sequence of `TYPE` values from the specified `srcQueue`.  Optionally
    /// specify a `basicAllocator` used to supply memory.  If
    /// `basicAllocator` is 0, the currently installed default allocator is
    /// used.
    Queue(const bdlc::Queue<TYPE>&  srcQueue,
          bslma::Allocator         *basicAllocator = 0);            // IMPLICIT
 
    /// Create a queue of objects of parameterized `TYPE` containing the
    /// sequence of `TYPE` values from the specified `srcQueue` and having
    /// either the specified `highWaterMark` suggested maximum length if
    /// `highWaterMark` is positive, or no maximum length if `highWaterMark`
    /// is negative.  Optionally specify a `basicAllocator` used to supply
    /// memory.  If `basicAllocator` is 0, the currently installed default allocator is used.  
    /// 
    /// \pre The behavior is undefined   unless
    /// `highWaterMark != 0`.
    Queue(const bdlc::Queue<TYPE>&  srcQueue,
          int                       highWaterMark,
          bslma::Allocator         *basicAllocator = 0);
 
    /// Destroy this container.  
    /// \pre The behavior is undefined  unless all access
    /// or modification of the container has completed prior to this call.
    ~Queue();
 
    // MANIPULATORS
 
    /// Remove the last item in this queue and load that item into the
    /// specified `buffer`.  If this queue is empty, block until an item is
    /// available.
    void popBack(TYPE *buffer);
 
    /// Remove the last item in this queue and return that item value.  If
    /// this queue is empty, block until an item is available.
    TYPE popBack();
 
    /// Remove the last item in this queue and load that item value into the
    /// specified `buffer`.  If this queue is empty, block until an item is
    /// available or until the specified `timeout` (expressed as the
    /// **ABSOLUTE** time from 00:00:00 UTC, January 1, 1970) expires.  Return
    /// 0 on success, and a non-zero value if the call timed out before an
    /// item was available.
    int timedPopBack(TYPE *buffer, const bsls::TimeInterval& timeout);
 
    /// Remove the first item in this queue and load that item into the
    /// specified `buffer`.  If the queue is empty, block until an item is
    /// available.
    void popFront(TYPE *buffer);
 
    /// Remove the first item in this queue and return that item value.  If
    /// the queue is empty, block until an item is available.
    TYPE popFront();
 
    /// Remove the first item in this queue and load that item value into
    /// the specified `buffer`.  If this queue is empty, block until an item
    /// is available or until the specified `timeout` (expressed as the
    /// **ABSOLUTE** time from 00:00:00 UTC, January 1, 1970) expires.  Return
    /// 0 on success, and a non-zero value if the call timed out before an
    /// item was available.
    int timedPopFront(TYPE *buffer, const bsls::TimeInterval& timeout);
 
    /// Remove all the items in this queue.  If the optionally specified
    /// `buffer` is not 0, load into `buffer` a copy of the items removed in
    /// front to back order of the queue prior to `removeAll`.
    void removeAll();
    void removeAll(bsl::vector<TYPE>      *buffer);
    void removeAll(std::vector<TYPE>      *buffer);
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
    void removeAll(std::pmr::vector<TYPE> *buffer);
#endif
 
    /// Append the specified `item` to the back of this queue.  If the
    /// high-water mark is non-negative and the number of items in this
    /// queue is greater than or equal to the high-water mark, then block
    /// until the number of items in this queue is less than the high-water
    /// mark.
    void pushBack(const TYPE& item);
 
    /// Append the specified `item` to the front of this queue.  If the
    /// high-water mark is non-negative and the number of items in this
    /// queue is greater than or equal to the high-water mark, then block
    /// until the number of items in this queue is less than the high-water
    /// mark.
    void pushFront(const TYPE& item);
 
    /// Append the specified `item` to the back of this queue.  If the
    /// high-water mark is non-negative and the number of items in this
    /// queue is greater than or equal to the high-water mark, then block
    /// until the number of items in this queue is less than the high-water
    /// mark or until the specified `timeout` (expressed as the **ABSOLUTE**
    /// time from 00:00:00 UTC, January 1, 1970) expires.  Return 0 on
    /// success, and a non-zero value if the call timed out before the
    /// number of items in this queue fell below the high-water mark.
    int timedPushBack(const TYPE& item, const bsls::TimeInterval& timeout);
 
    /// Append the specified `item` to the front of this queue.  If the high
    /// water mark is non-negative and the number of items in this queue is
    /// greater than or equal to the high-water mark, then block until the
    /// number of items in this queue is less than the high-water mark or
    /// until the specified `timeout` (expressed as the **ABSOLUTE** time from
    /// 00:00:00 UTC, January 1, 1970) expires.  Return 0 on success, and a
    /// non-zero value if the call timed out before the number of items in
    /// this queue fell below the high-water mark.
    int timedPushFront(const TYPE& item, const bsls::TimeInterval& timeout);
 
    /// Append the specified `item` to the front of this queue without regard for the high-water mark.  
    /// 
    /// \note Note that   this method is provided
    /// to allow high priority items to be inserted when the queue is full
    /// (i.e., has a number of items greater than or equal to its high-water
    /// mark); `pushFront` and `pushBack` should be used for general use.
    void forcePushFront(const TYPE& item);
 
    /// If this queue is non-empty, remove the first item, load that item
    /// into the specified `buffer`, and return 0 indicating success.  If
    /// this queue is empty, return a non-zero value with no effect on
    /// `buffer` or the state of this queue.  This method never blocks.
    int tryPopFront(TYPE *buffer);
 
    // Remove up to the specified `maxNumItems` from the front of this
    // queue.  Optionally specify a `buffer` into which the items removed
    // from the queue are loaded.  If `buffer` is non-null, the removed
    // items are appended to it as if by repeated application of
    // `buffer->push_back(popFront())` while the queue is not empty and
    // `maxNumItems` have not yet been removed.  The behavior is undefined
    // unless `maxNumItems >= 0`.  This method never blocks.
    void tryPopFront(int maxNumItems);
    void tryPopFront(int maxNumItems, bsl::vector<TYPE>      *buffer);
    void tryPopFront(int maxNumItems, std::vector<TYPE>      *buffer);
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
    void tryPopFront(int maxNumItems, std::pmr::vector<TYPE> *buffer);
#endif
 
    /// If this queue is non-empty, remove the last item, load that item into
    /// the specified `buffer`, and return 0 indicating success.  If this queue
    /// is empty, return a non-zero value with no effect on `buffer` or the
    /// state of this queue.  This method never blocks.
    int tryPopBack(TYPE *buffer);
 
    // Remove up to the specified `maxNumItems` from the back of this
    // queue.  Optionally specify a `buffer` into which the items removed
    // from the queue are loaded.  If `buffer` is non-null, the removed
    // items are appended to it as if by repeated application of
    // `buffer->push_back(popBack())` while the queue is not empty and
    // `maxNumItems` have not yet been removed.  This method never blocks.
    // The behavior is undefined unless `maxNumItems >= 0`.  Note that the
    // ordering of the items in `*buffer` after the call is the reverse of
    // the ordering they had in the queue.
    void tryPopBack(int maxNumItems);
    void tryPopBack(int maxNumItems, bsl::vector<TYPE>      *buffer);
    void tryPopBack(int maxNumItems, std::vector<TYPE>      *buffer);
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
    void tryPopBack(int maxNumItems, std::pmr::vector<TYPE> *buffer);
#endif
 
    // *** Modifiable access to the mutex, condition variable, and queue ***
 
    /// Return a reference to the modifiable condition variable used by this
    /// queue to signal that the queue is not empty.
    ///
    /// @deprecated  Use @ref notEmptyCondition instead.
    bslmt::Condition& condition();
 
    /// Return a reference to the modifiable condition variable used by this
    /// queue to signal that the queue is not full (i.e., has fewer items
    /// than its high-water mark).
    ///
    /// @deprecated  Use @ref notFullCondition instead.
    bslmt::Condition& insertCondition();
 
    /// Return a reference to the modifiable mutex used by this queue to
    /// synchronize access to its underlying `bdlc::Queue` object.
    bslmt::Mutex& mutex();
 
    /// Return the condition variable used by this queue to signal that the
    /// queue is not empty.
    bslmt::Condition& notEmptyCondition();
 
    /// Return the condition variable used by this queue to signal that the
    /// queue is not full (i.e., has fewer items than its high-water mark).
    bslmt::Condition& notFullCondition();
 
    /// Return a reference to the modifiable underlying `bdlc::Queue` object
    /// used by this queue.  Any access to the returned queue MUST first
    /// lock the associated mutex object (see the `mutex` method) in a
    /// multi-threaded environment.  And when items are directly added to
    /// the queue returned by this method, the associated condition variable
    /// (see the `condition` method) should be signaled to notify any
    /// waiting threads of the availability of the new data.
    ///
    /// The (error-prone) usage of this method will be replaced by an
    /// appropriate smart-pointer-like proctor object in the future.
    /// Meanwhile, use this method with caution.
    bdlc::Queue<TYPE>& queue();
 
    // ACCESSORS
 
    /// Return the high-water mark value for this queue.  
    /// \note Note that  a negative
    /// value indicates no suggested-maximum capacity, and is not necessarily
    /// the same negative value that was passed to the constructor.
    int highWaterMark() const;
 
    /// Return the number of elements in this queue.  
    /// \note Note that  if other
    /// threads are manipulating the queue, this information may be obsolete by
    /// the time it is returned.
    int length() const;
};
 
                        // ======================
                        // struct Queue::IsVector
                        // ======================
 
/// This `struct` has a `value` that evaluates to `true` if the specified
/// `VECTOR` is a `bsl`, `std`, or `std::pmr` `vector<TYPE>`.
template <class TYPE>
template <class VECTOR>
struct Queue<TYPE>::IsVector {
 
    static const bool value =
                            bsl::is_same<bsl::vector<TYPE>, VECTOR>::value
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
                         || bsl::is_same<std::pmr::vector<TYPE>, VECTOR>::value
#endif
                         || bsl::is_same<std::vector<TYPE>, VECTOR>::value;
};
 
// ============================================================================
//                            INLINE DEFINITIONS
// ============================================================================
 
// PRIVATE MANIPULATORS
template <class TYPE>
template <class VECTOR>
void Queue<TYPE>::removeAllImp(VECTOR *buffer)
{
    BSLMF_ASSERT(IsVector<VECTOR>::value);
 
    bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
    bool wasFull = d_highWaterMark > 0 && d_queue.length() >= d_highWaterMark;
 
    if (buffer) {
        for (int ii = 0, len = d_queue.length(); ii < len; ++ii) {
            buffer->push_back(bslmf::MovableRefUtil::move(d_queue[ii]));
        }
    }
    d_queue.removeAll();
 
    lock.release()->unlock();
 
    if (wasFull) {
        for (int i = 0; d_highWaterMark > i; ++i) {
            d_notFullCondition.signal();
        }
    }
}
 
template <class TYPE>
template <class VECTOR>
void Queue<TYPE>::tryPopFrontImp(int maxNumItems, VECTOR *buffer)
{
    BSLMF_ASSERT(IsVector<VECTOR>::value);
 
    int numSignal = 0;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        int        length  = d_queue.length();
        const bool wasFull = d_highWaterMark > 0 && length >= d_highWaterMark;
 
        for (; d_queue.length() > 0 && maxNumItems > 0; --maxNumItems) {
            if (buffer) {
                buffer->push_back(
                                 bslmf::MovableRefUtil::move(d_queue.front()));
            }
            d_queue.popFront();
            --length;
        }
 
        if (wasFull && length < d_highWaterMark) {
            numSignal = d_highWaterMark - length;
        }
    }
 
    for (; 0 < numSignal; --numSignal) {
        d_notFullCondition.signal();
    }
}
 
template <class TYPE>
template <class VECTOR>
void Queue<TYPE>::tryPopBackImp(int maxNumItems, VECTOR *buffer)
{
    BSLMF_ASSERT(IsVector<VECTOR>::value);
 
    int numSignal = 0;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        int        length  = d_queue.length();
        const bool wasFull = d_highWaterMark > 0 && length >= d_highWaterMark;
 
        for (; d_queue.length() > 0 && maxNumItems > 0; --maxNumItems) {
            if (buffer) {
                buffer->push_back(bslmf::MovableRefUtil::move(d_queue.back()));
            }
            d_queue.popBack();
            --length;
        }
 
        if (wasFull && length < d_highWaterMark) {
            numSignal = d_highWaterMark - length;
        }
    }
 
    for (; 0 < numSignal; --numSignal) {
        d_notFullCondition.signal();
    }
}
 
// CREATORS
template <class TYPE>
inline
Queue<TYPE>::Queue(bslma::Allocator *basicAllocator)
: d_queue(basicAllocator)
, d_highWaterMark(-1)
{
}
 
template <class TYPE>
inline
Queue<TYPE>:: Queue(const InitialCapacity&  numItems,
                    bslma::Allocator       *basicAllocator)
: d_queue(QueueCapacity(numItems.d_i), basicAllocator)
, d_highWaterMark(-1)
{
}
 
template <class TYPE>
inline
Queue<TYPE>::Queue(int highWaterMark, bslma::Allocator *basicAllocator)
: d_queue(basicAllocator)
, d_highWaterMark(highWaterMark < 0 ? -1 : highWaterMark)
{
}
 
template <class TYPE>
inline
Queue<TYPE>::Queue(const InitialCapacity&  numItems,
                   int                     highWaterMark,
                   bslma::Allocator       *basicAllocator)
: d_queue(QueueCapacity(numItems.d_i), basicAllocator)
, d_highWaterMark(highWaterMark < 0 ? -1 : highWaterMark)
{
}
 
template <class TYPE>
inline
Queue<TYPE>::Queue(const bdlc::Queue<TYPE>&  srcQueue,
                   bslma::Allocator         *basicAllocator)
: d_queue(srcQueue, basicAllocator)
, d_highWaterMark(-1)
{
}
 
template <class TYPE>
inline
Queue<TYPE>::Queue(const bdlc::Queue<TYPE>&  srcQueue,
                   int                       highWaterMark,
                   bslma::Allocator         *basicAllocator)
: d_queue(srcQueue, basicAllocator)
, d_highWaterMark(highWaterMark < 0 ? -1 : highWaterMark)
{
}
 
template <class TYPE>
inline
Queue<TYPE>::~Queue()
{
}
 
// MANIPULATORS
template <class TYPE>
void Queue<TYPE>::popBack(TYPE *buffer)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        while (0 == (length = d_queue.length())) {
            d_notEmptyCondition.wait(&d_mutex);
        }
        *buffer = d_queue.back();
        d_queue.popBack();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
}
 
template <class TYPE>
TYPE Queue<TYPE>::popBack()
{
    // Note that this method is not implemented in terms of 'popBack(TYPE*)'
    // because that would require TYPE to have a default constructor.
 
    unsigned int length;
 
    bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
    while (0 == (length = d_queue.length())) {
        d_notEmptyCondition.wait(&d_mutex);
    }
    TYPE back = d_queue.back();
    d_queue.popBack();
    --length;
 
    lock.release()->unlock();
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return back;
}
 
template <class TYPE>
int Queue<TYPE>::timedPopBack(TYPE *buffer, const bsls::TimeInterval& timeout)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        while (0 == (length = d_queue.length())) {
            if (d_notEmptyCondition.timedWait(&d_mutex, timeout)) {
                return 1;                                             // RETURN
            }
        }
        *buffer = d_queue.back();
        d_queue.popBack();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return 0;
}
 
template <class TYPE>
void Queue<TYPE>::popFront(TYPE *buffer)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        while (0 == (length = d_queue.length())) {
            d_notEmptyCondition.wait(&d_mutex);
        }
        *buffer = d_queue.front();
        d_queue.popFront();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
}
 
template <class TYPE>
TYPE Queue<TYPE>::popFront()
{
    // Note that this method is not implemented in terms of 'popFront(TYPE*)'
    // because that would require TYPE to have a default constructor.
 
    unsigned int length;
 
    bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
    while (0 == (length = d_queue.length())) {
        d_notEmptyCondition.wait(&d_mutex);
    }
    TYPE front = d_queue.front();
    d_queue.popFront();
    --length;
 
    lock.release()->unlock();
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return front;
}
 
template <class TYPE>
int Queue<TYPE>::timedPopFront(TYPE *buffer, const bsls::TimeInterval& timeout)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        while (0 == (length = d_queue.length())) {
            if (d_notEmptyCondition.timedWait(&d_mutex, timeout)) {
                return 1;                                             // RETURN
            }
        }
        *buffer = d_queue.front();
        d_queue.popFront();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return 0;
}
 
template <class TYPE>
int Queue<TYPE>::tryPopFront(TYPE *buffer)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        if (0 == (length = d_queue.length())) {
            return 1;                                                 // RETURN
        }
        *buffer = d_queue.front();
        d_queue.popFront();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return 0;
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopFront(int maxNumItems)
{
    tryPopFrontImp(maxNumItems, static_cast<bsl::vector<TYPE> *>(0));
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopFront(int maxNumItems, bsl::vector<TYPE> *buffer)
{
    tryPopFrontImp(maxNumItems, buffer);
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopFront(int maxNumItems, std::vector<TYPE> *buffer)
{
    tryPopFrontImp(maxNumItems, buffer);
}
 
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
template <class TYPE>
inline
void Queue<TYPE>::tryPopFront(int maxNumItems, std::pmr::vector<TYPE> *buffer)
{
    tryPopFrontImp(maxNumItems, buffer);
}
#endif
 
template <class TYPE>
int Queue<TYPE>::tryPopBack(TYPE *buffer)
{
    unsigned int length;
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
        if (0 == (length = d_queue.length())) {
            return 1;                                                 // RETURN
        }
        *buffer = d_queue.back();
        d_queue.popBack();
        --length;
    }
 
    if (length < (unsigned) d_highWaterMark) {
        d_notFullCondition.signal();
    }
    return 0;
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopBack(int maxNumItems)
{
    tryPopBackImp(maxNumItems, static_cast<bsl::vector<TYPE> *>(0));
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopBack(int maxNumItems, bsl::vector<TYPE> *buffer)
{
    tryPopBackImp(maxNumItems, buffer);
}
 
template <class TYPE>
inline
void Queue<TYPE>::tryPopBack(int maxNumItems, std::vector<TYPE> *buffer)
{
    tryPopBackImp(maxNumItems, buffer);
}
 
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
template <class TYPE>
inline
void Queue<TYPE>::tryPopBack(int maxNumItems, std::pmr::vector<TYPE> *buffer)
{
    tryPopBackImp(maxNumItems, buffer);
}
#endif
 
template <class TYPE>
void Queue<TYPE>::removeAll()
{
    removeAllImp(static_cast<bsl::vector<TYPE> *>(0));
}
 
template <class TYPE>
void Queue<TYPE>::removeAll(bsl::vector<TYPE> *buffer)
{
    removeAllImp(buffer);
}
 
template <class TYPE>
void Queue<TYPE>::removeAll(std::vector<TYPE> *buffer)
{
    removeAllImp(buffer);
}
 
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_PMR
template <class TYPE>
void Queue<TYPE>::removeAll(std::pmr::vector<TYPE> *buffer)
{
    removeAllImp(buffer);
}
#endif
 
template <class TYPE>
void Queue<TYPE>::pushBack(const TYPE& item)
{
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
        if (d_highWaterMark >= 0) {
            while (d_queue.length() >= d_highWaterMark) {
                d_notFullCondition.wait(&d_mutex);
            }
        }
        d_queue.pushBack(item);
    }
 
    d_notEmptyCondition.signal();
}
 
template <class TYPE>
void Queue<TYPE>::pushFront(const TYPE& item)
{
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
        if (d_highWaterMark >= 0) {
            while (d_queue.length() >= d_highWaterMark) {
                d_notFullCondition.wait(&d_mutex);
            }
        }
        d_queue.pushFront(item);
    }
 
    d_notEmptyCondition.signal();
}
 
template <class TYPE>
int Queue<TYPE>::timedPushBack(const TYPE&               item,
                               const bsls::TimeInterval& timeout)
{
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
        if (d_highWaterMark >= 0) {
            while (d_queue.length() >= d_highWaterMark) {
                if (d_notFullCondition.timedWait(&d_mutex, timeout)) {
                    return 1;                                         // RETURN
                }
            }
        }
        d_queue.pushBack(item);
    }
 
    d_notEmptyCondition.signal();
    return 0;
}
 
template <class TYPE>
int Queue<TYPE>::timedPushFront(const TYPE&               item,
                                const bsls::TimeInterval& timeout)
{
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
        if (d_highWaterMark >= 0) {
            while (d_queue.length() >= d_highWaterMark) {
                if (d_notFullCondition.timedWait(&d_mutex, timeout)) {
                    return 1;                                         // RETURN
                }
            }
        }
        d_queue.pushFront(item);
    }
 
    d_notEmptyCondition.signal();
    return 0;
}
 
template <class TYPE>
inline
void Queue<TYPE>::forcePushFront(const TYPE& item)
{
    {
        bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
        d_queue.pushFront(item);
    }
    d_notEmptyCondition.signal();
}
 
// *** Modifiable access to the mutex, condition variable, and queue ***
 
template <class TYPE>
inline
bslmt::Condition& Queue<TYPE>::condition()
{
    return d_notEmptyCondition;
}
 
template <class TYPE>
inline
bslmt::Condition& Queue<TYPE>::insertCondition()
{
    return d_notFullCondition;
}
 
template <class TYPE>
inline
bslmt::Mutex& Queue<TYPE>::mutex()
{
    return d_mutex;
}
 
template <class TYPE>
inline
bslmt::Condition& Queue<TYPE>::notEmptyCondition()
{
    return d_notEmptyCondition;
}
 
template <class TYPE>
inline
bslmt::Condition& Queue<TYPE>::notFullCondition()
{
    return d_notFullCondition;
}
 
template <class TYPE>
inline
bdlc::Queue<TYPE>& Queue<TYPE>::queue()
{
    return d_queue;
}
 
// ACCESSORS
template <class TYPE>
inline
int Queue<TYPE>::highWaterMark() const
{
    return d_highWaterMark;
}
 
template <class TYPE>
inline
int Queue<TYPE>::length() const
{
    bslmt::LockGuard<bslmt::Mutex> lock(&d_mutex);
 
    return d_queue.length();
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */