bslmt_threadattributes.h

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/// @file bslmt_threadattributes.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmt_threadattributes.h                                           -*-C++-*-
#ifndef INCLUDED_BSLMT_THREADATTRIBUTES
#define INCLUDED_BSLMT_THREADATTRIBUTES
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmt_threadattributes bslmt_threadattributes
/// @brief  Provide a description of the attributes of a thread.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmt
/// @{
/// @addtogroup bslmt_threadattributes
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmt_threadattributes-purpose"> Purpose</a>
/// * <a href="#bslmt_threadattributes-classes"> Classes </a>
/// * <a href="#bslmt_threadattributes-description"> Description </a>
///   * <a href="#bslmt_threadattributes-attributes"> Attributes </a>
///     * <a href="#bslmt_threadattributes-detachedstate-attribute"> detachedState Attribute </a>
///     * <a href="#bslmt_threadattributes-stacksize-attribute"> stackSize Attribute </a>
///     * <a href="#bslmt_threadattributes-guardsize-attribute"> guardSize Attribute </a>
///     * <a href="#bslmt_threadattributes-inheritschedule-attribute"> inheritSchedule Attribute </a>
///     * <a href="#bslmt_threadattributes-schedulingpolicy-attribute"> schedulingPolicy Attribute </a>
///     * <a href="#bslmt_threadattributes-schedulingpriority-attribute"> schedulingPriority Attribute </a>
///     * <a href="#bslmt_threadattributes-threadname-attribute"> threadName Attribute </a>
///   * <a href="#bslmt_threadattributes-fluent-interface"> Fluent Interface </a>
///   * <a href="#bslmt_threadattributes-usage"> Usage </a>
///     * <a href="#bslmt_threadattributes-example-1-creating-and-modifying-thread-attributes-objects"> Example 1: Creating and Modifying Thread Attributes Objects </a>
///
/// # Purpose {#bslmt_threadattributes-purpose}
/// Provide a description of the attributes of a thread.
///
/// # Classes {#bslmt_threadattributes-classes}
///
/// -  bslmt::ThreadAttributes: description of the attributes of a thread
///
/// @see  bslmt_threadutil, bslmt_configuration
///
/// # Description {#bslmt_threadattributes-description}
/// This component provides a simply constrained (value-semantic)
/// attribute class, `bslmt::ThreadAttributes`, for describing attributes of a
/// thread in a platform-independent way.
///
/// ## Attributes {#bslmt_threadattributes-attributes}
///
///
/// The default values and constraints for the attributes provided by
/// `bslmt::ThreadAttributes` are listed in the following two tables:
/// @code
/// Name                Type                   Default
/// ------------------  ---------------------  ----------------------
/// detachedState       enum DetachedState     e_CREATE_JOINABLE
/// stackSize           int                    e_UNSET_STACK_SIZE
/// guardSize           int                    e_UNSET_GUARD_SIZE
/// inheritSchedule     bool                   'true'
/// schedulingPolicy    enum SchedulingPolicy  e_SCHED_DEFAULT
/// schedulingPriority  int                    e_UNSET_PRIORITY
/// threadName          bsl::string            ""
///
/// Name          Constraint
/// ---------     ---------------------------------------------------
/// stackSize     'e_UNSET_STACK_SIZE == stackSize || 0 <= stackSize'
/// guardSize     'e_UNSET_GUARD_SIZE == guardSize || 0 <= guardSize'
/// @endcode
///
/// ### detachedState Attribute {#bslmt_threadattributes-detachedstate-attribute}
///
///
/// The `detachedState` attribute indicates whether an associated thread should
/// be created in a joinable or detached state, through the enum values
/// `e_CREATE_JOINABLE` and `e_CREATE_DETACHED`, respectively.  A thread in the
/// joinable state will have its exit status maintained after thread
/// termination.  Any thread can join with a joinable thread (see
/// @ref bslmt_threadutil ), in which case the joining thread will block, waiting
/// for the joined thread's execution to complete, after which the joined
/// thread's termination status will be reported back to the joining thread, and
/// its resources reclaimed.  A thread in a detached state will have its
/// resources claimed at thread termination, and cannot be joined.  Note that a
/// joinable thread can be made detached after it is created, but not vice
/// versa.
///
/// ### stackSize Attribute {#bslmt_threadattributes-stacksize-attribute}
///
///
/// The `stackSize` attribute indicates the size, in bytes, of the stack that
/// should be provided to a newly created thread.  If the stack size is
/// `e_UNSET_STACK_SIZE` then a created thread will be provided a default stack
/// size (see @ref bslmt_configuration ).  The `stackSize` attribute should be
/// interpreted to mean that a created thread can safely define an automatic
/// variable of the configured `stackSize` bytes in its thread-entry function.
/// Note that, on some platforms, an adjusted value derived from the `stackSize`
/// attribute may be supplied to the underlying representation by the thread
/// creation function.
///
/// ### guardSize Attribute {#bslmt_threadattributes-guardsize-attribute}
///
///
/// The `guardSize` attribute indicates the size of the memory region to provide
/// past the end of a created thread's stack to protect against stack overflows.
/// If a thread's stack pointer overflows into a guard area, the task will
/// receive an error (e.g., a signal).  If `guardSize` is `e_UNSET_GUARD_SIZE`,
/// then a created thread will be provided with a default native guard size (see
/// @ref bslmt_configuration ).  Note that the interpretation of `guardSize` may
/// vary among platforms, and the value may be adjusted up (e.g., by rounding up
/// to a multiple of page size) or ignored entirely (e.g., the Windows platform
/// does not support this attribute).
///
/// ### inheritSchedule Attribute {#bslmt_threadattributes-inheritschedule-attribute}
///
///
/// The `inheritSchedule` attribute, if `true`, indicates that a created
/// thread's `schedulingPolicy` and `schedulingPriority` attributes should be
/// taken from its parent thread and the configured values of those thread
/// attributes should be ignored.  If `inheritSchedule` is `false`, then the
/// `schedulingPolicy` and `schedulingPriority` attribute values should be used
/// to configure a thread.  See @ref bslmt_threadutil  for information about support
/// for this attribute.
///
/// ### schedulingPolicy Attribute {#bslmt_threadattributes-schedulingpolicy-attribute}
///
///
/// The `schedulingPolicy` attribute indicates the policy that should be used to
/// schedule the created thread for execution.  Typically clients should use the
/// default platform supplied scheduling policy, which is indicated by the
/// `e_SCHED_DEFAULT` value.  The alternative scheduling policies,
/// `e_THREAD_FIFO` and `e_SCHED_RR`, are "real-time" scheduling policies, and
/// may not be available unless the task is run with the appropriate privileges.
/// `e_SCHED_FIFO` indicates a thread should run until it either yields or is
/// interrupted by a thread of higher priority.  `e_SCHED_RR` is the same as
/// `e_SCHED_FIFO`, except that the created thread may be interrupted by a ready
/// thread of equal priority after a finite time-slice.  This attribute is
/// ignored unless `inheritSchedule` is `false`.  See @ref bslmt_threadutil  for
/// information about support for this attribute.
///
/// ### schedulingPriority Attribute {#bslmt_threadattributes-schedulingpriority-attribute}
///
///
/// The `schedulingPriority` attribute is a platform specific value whose valid
/// values range from the minimum to the maximum value for the associated
/// `schedulingPolicy`, with higher numbers indicating a more urgent priority.
/// Functions to obtain the minimum and maximum values are in this component and
/// @ref bslmt_threadutil .  This attribute is ignored unless `inheritSchedule` is
/// `false`.  See @ref bslmt_threadutil  for information about support for this
/// attribute.
///
/// ### threadName Attribute {#bslmt_threadattributes-threadname-attribute}
///
///
/// The `threadName` attribute indicates the name the thread is to have.  Thread
/// names show up in debuggers on some platforms, and are unsupported on others.
/// Thread names have unlimited lengths in a thread attributes object, but the
/// thread names actually supported by specific platforms may have limited
/// length, depending upon the platform, so thread names may be truncated when
/// assigned to the actual thread.  At this time, only Linux, Solaris, Darwin,
/// and Windows support thread names.  Unix platforms have a maximum thread name
/// length of 15, while on Windows, the limit is 32767, or `(1 << 15) - 1`
/// characters.
///
/// ## Fluent Interface {#bslmt_threadattributes-fluent-interface}
///
///
/// `bslmt::ThreadAttributes` provides manipulators that return a non-`const`
/// reference to the object so that setting individual attributes can be
/// "chained" into a single expression statement, or that attributes can be
/// "built" in place as a function argument.  For example:
/// @code
/// bslmt::ThreadUtil::Handle handle;
///
/// int status = bslmt::ThreadUtil::create(
///                         &handle,
///                         bslmt::ThreadAttributes().setThreadName("myName")
///                                                  .setInheritSchedule(true),
///                         myThreadFunction,
///                         &myThreadArgument);
/// @endcode
///
/// ## Usage {#bslmt_threadattributes-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Creating and Modifying Thread Attributes Objects {#bslmt_threadattributes-example-1-creating-and-modifying-thread-attributes-objects}
///
///
/// In this example we will demonstrate creating and configuring a
/// `bslmt::ThreadAttributes` object, then using it with a hypothetical
/// thread-creation function.  Finally we show how a thread creation function
/// might interpret those attributes for the underlying operating system.
///
/// First we forward declare a routine that we will use to create a thread:
/// @code
/// // Spawn a thread having properties described by the specified
/// // `attributes` and that runs the specified `function`, and assign a
/// // handle referring to the spawned thread to the specified
/// // `*threadHandle`.
/// void myThreadCreate(int                             *threadHandle,
///                     const bslmt::ThreadAttributes&   attributes,
///                     void                           (*function)());
/// @endcode
/// Then, we declare two routines that will return the minimum and maximum
/// thread priority given a scheduling policy.  Note that similar methods exist
/// in @ref bslmt_threadutil .
/// @code
/// int myMinPriority(bslmt::ThreadAttributes::SchedulingPolicy policy);
/// int myMaxPriority(bslmt::ThreadAttributes::SchedulingPolicy policy);
/// @endcode
/// Next we define a function that we will use as our thread entry point.  This
/// function declares a single variable on the stack of predetermined size.
/// @code
/// enum { k_BUFFER_SIZE = 128 * 1024 };
///
/// void myThreadFunction()
/// {
///     int bufferLocal[k_BUFFER_SIZE];
///
///     // Perform some calculation that involves no subroutine calls or
///     // additional automatic variables.
/// }
/// @endcode
/// Then, we define our main function, in which we demonstrate configuring a
/// `bslmt::ThreadAttributes` object describing the properties a thread we will
/// create.
/// @code
/// void testMain()
/// {
/// @endcode
/// Next, we create a thread attributes object, `attributes`, and set its
/// `stackSize` attribute to a value large enough to accommodate the
/// `BUFFER_SIZE` buffer used by `myThreadFunction`.  Note that we use
/// `BUFFER_SIZE` as an illustration; in practice, it is difficult or impossible
/// to gauge the exact amount of stack size required for a typical thread, and
/// the value supplied should be a reasonable *upper* bound on the anticipated
/// requirement.
/// @code
///     bslmt::ThreadAttributes attributes;
///     attributes.setStackSize(k_BUFFER_SIZE);
/// @endcode
/// Then, we set the `detachedState` property to `e_CREATE_DETACHED`, indicating
/// that the thread will not be joinable, and its resources will be reclaimed
/// upon termination.
/// @code
///     attributes.setDetachedState(
///                            bslmt::ThreadAttributes::e_CREATE_DETACHED);
/// @endcode
/// Now, we create a thread, using the attributes configured above:
/// @code
///     int handle;
///     myThreadCreate(&handle, attributes, &myThreadFunction);
/// }
/// @endcode
/// Finally, we define the thread creation function, and show how a thread
/// attributes object might be interpreted by it:
/// @code
/// /// Spawn a thread with properties described by the specified
/// /// `attributes`, running the specified `function`, and assign a handle
/// /// referring to the spawned thread to the specified `*threadHandle`.
/// void myThreadCreate(int                             *threadHandle,
///                     const bslmt::ThreadAttributes&   attributes,
///                     void                           (*function)())
/// {
///     int stackSize = attributes.stackSize();
///     if (bslmt::ThreadAttributes::e_UNSET_STACK_SIZE == stackSize) {
///         stackSize = bslmt::Configuration::defaultThreadStackSize();
///     }
///
///     // Add a "fudge factor" to `stackSize` to ensure that the client can
///     // declare an object of `stackSize` bytes on the stack safely.
///
///     stackSize += 8192;
///
///     int guardSize = attributes.guardSize();
///     if (bslmt::ThreadAttributes::e_UNSET_GUARD_SIZE == guardSize) {
///         guardSize = bslmt::Configuration::nativeDefaultThreadGuardSize();
///     }
///
///     int policy = attributes.schedulingPolicy();
///     int priority = attributes.schedulingPriority();
///
///     // the following is pseudo-code for actually creating the thread
///     /*
///     if (bslmt::ThreadAttributes::e_UNSET_PRIORITY == priority) {
///         priority = operatingSystemDefaultPriority(policy);
///     }
///
///     operatingSystemThreadCreate(threadHandle,
///                                 stackSize,
///                                 guardSize,
///                                 attributes.inheritSchedule(),
///                                 policy,
///                                 priority,
///                                 attributes.detachedState()
///                                 function);
///     */
/// }
/// @endcode
/// Notice that a new value derived from the `stackSize` attribute is used so
/// that the meaning of the attribute is platform neutral.
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslmt
 * @{
 */
/** @addtogroup bslmt_threadattributes
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslma_allocator.h>
#include <bslma_usesbslmaallocator.h>
 
#include <bslmf_assert.h>
#include <bslmf_nestedtraitdeclaration.h>
 
#include <bsls_assert.h>
#include <bsls_platform.h>
 
#include <bsl_c_limits.h>
#include <bsl_iosfwd.h>
#include <bsl_string.h>
 
 
namespace bslmt {
 
                          // ======================
                          // class ThreadAttributes
                          // ======================
 
/// This simply constrained (value-semantic) attribute class characterizes a
/// collection of thread attribute values.  See the @ref bslmt_threadattributes-attributes  section for
/// information on the class attributes.
///
/// This class:
/// * supports a complete set of *value* *semantic* operations
///   - except for `bdex` serialization
/// * is *exception-neutral*
/// * is *alias-safe*
/// * is `const` *thread-safe*
/// For terminology see @ref bsldoc_glossary .
///
/// See @ref bslmt_threadattributes 
class ThreadAttributes {
 
  public:
    // PUBLIC TYPES
 
    /// This enumeration provides two values used to distinguish among a
    /// joinable thread and a non-joinable (detached) thread.
    enum DetachedState {
 
        e_CREATE_JOINABLE = 0,  // create a joinable thread
        e_CREATE_DETACHED = 1   // create a non-joinable thread
 
#ifndef BDE_OMIT_INTERNAL_DEPRECATED
      , BCEMT_CREATE_JOINABLE = e_CREATE_JOINABLE
      , BCEMT_CREATE_DETACHED = e_CREATE_DETACHED
      , CREATE_JOINABLE = e_CREATE_JOINABLE
      , CREATE_DETACHED = e_CREATE_DETACHED
#endif // BDE_OMIT_INTERNAL_DEPRECATED
    };
 
    enum SchedulingPolicy {
        // This enumeration provides values used to distinguish between
        // different thread scheduling policies.
 
        e_SCHED_OTHER   = 0,  // unspecified, OS-dependent scheduling
                                  // policy
 
        e_SCHED_FIFO    = 1,  // first-in-first-out scheduling policy
 
        e_SCHED_RR      = 2,  // round-robin scheduling policy
 
        e_SCHED_DEFAULT = 3   // default OS scheduling policy, usually
                              // equivalent to 'e_SCHED_OTHER'
#ifndef BDE_OMIT_INTERNAL_DEPRECATED
      , BCEMT_SCHED_OTHER = e_SCHED_OTHER
      , BCEMT_SCHED_FIFO = e_SCHED_FIFO
      , BCEMT_SCHED_RR = e_SCHED_RR
      , BCEMT_SCHED_DEFAULT = e_SCHED_DEFAULT
#endif  // BDE_OMIT_INTERNAL_DEPRECATED
    };
 
    /// The following constants indicate that the `stackSize`, `guardSize`,
    /// and `schedulingPriority` attributes, respectively, are unspecified
    /// and the thread creation routine is use platform-specific defaults.
    /// These attributes are initialized to these values when a thread
    /// attributes object is default constructed.
    enum {
 
        e_UNSET_STACK_SIZE = -1,
        e_UNSET_GUARD_SIZE = -1,
        e_UNSET_PRIORITY   = INT_MIN,
 
        e_SCHED_MIN        = e_SCHED_OTHER,
        e_SCHED_MAX        = e_SCHED_DEFAULT
#ifndef BDE_OMIT_INTERNAL_DEPRECATED
      , BCEMT_UNSET_STACK_SIZE = e_UNSET_STACK_SIZE
      , BCEMT_UNSET_GUARD_SIZE = e_UNSET_GUARD_SIZE
      , BCEMT_UNSET_PRIORITY = e_UNSET_PRIORITY
      , BCEMT_SCHED_MIN = e_SCHED_MIN
      , BCEMT_SCHED_MAX = e_SCHED_MAX
#endif  // BDE_OMIT_INTERNAL_DEPRECATED
    };
 
  private:
    // DATA
    DetachedState    d_detachedState;       // whether the thread is detached
                                            // or joinable
 
    int              d_guardSize;           // size of guard area provided
                                            // beyond the end of the configured
                                            // thread's stack
 
    bool             d_inheritScheduleFlag; // whether the thread inherits its
                                            // scheduling policy & priority
                                            // from its parent thread
 
    SchedulingPolicy d_schedulingPolicy;    // policy for scheduling thread
                                            // execution
 
    int              d_schedulingPriority;  // thread priority (higher numbers
                                            // indicate more urgency)
 
    int              d_stackSize;           // size of the thread's stack
 
    bsl::string      d_threadName;          // name of the thread
 
  public:
    // TRAITS
    BSLMF_NESTED_TRAIT_DECLARATION(ThreadAttributes,
                                   bslma::UsesBslmaAllocator);
 
    // CREATORS
 
    ThreadAttributes();
    /// Create a `ThreadAttributes` object having the (default) attribute
    /// values:
    /// * `detachedState()      == e_CREATE_JOINABLE`
    /// * `guardSize()          == e_UNSET_GUARD_SIZE`
    /// * `inheritSchedule()    == true`
    /// * `schedulingPolicy()   == e_SCHED_DEFAULT`
    /// * `schedulingPriority() == e_UNSET_PRIORITY`
    /// * `stackSize()          == e_UNSET_STACK_SIZE`
    /// * `threadName()         == ""`
    /// Optionally specify a `basicAllocator` used to supply memory.  If
    /// `basicAllocator` is 0, the currently installed default allocator is
    /// used.
    explicit ThreadAttributes(bslma::Allocator *basicAllocator);
 
    /// Create a `ThreadAttributes` object having the same value as the
    /// specified `original` object.  Optionally specify a `basicAllocator`
    /// used to supply memory.  If `basicAllocator` is 0, the currently
    /// installed default allocator is used.
    ThreadAttributes(const ThreadAttributes&  original,
                     bslma::Allocator        *basicAllocator = 0);
 
    // MANIPULATORS
 
    /// Assign to this object the value of the specified `rhs` object, and
    /// return a reference providing modifiable access to this object.
    ThreadAttributes& operator=(const ThreadAttributes& rhs);
 
    // MANIPULATORS
 
    /// Set the `detachedState` attribute of this object to the specified
    /// `value`.  Return a non-`const` reference to this object (see also
    /// {Fluent Interface}).  A value of `e_CREATE_JOINABLE` (the default)
    /// indicates that a thread must be joined to clean up its resources
    /// after it terminates; a value of `e_CREATE_DETACHED` (the only other
    /// legal value) indicates that the resources will be cleaned up
    /// automatically upon thread termination, and that the thread must not
    /// be joined.
    ThreadAttributes& setDetachedState(DetachedState value);
 
    /// Set the `guardSize` attribute of this object to the specified
    /// `value` (in bytes).  Return a non-`const` reference to this object
    /// (see also {Fluent Interface}).  `e_UNSET_GUARD_SIZE == guardSize` is
    /// intended to indicate that the default value as defined by the
    /// platform is to be used.  This default value is typically the size of
    /// one or two pages (see @ref bslmt_configuration ).  The behavior is
    /// undefined unless `e_UNSET_GUARD_SIZE == guardSize` or
    /// `guardSize >= 0`.
    ThreadAttributes& setGuardSize(int value);
 
    /// Set the `inheritSchedule` attribute of this object to the specified
    /// `value`.  Return a non-`const` reference to this object (see also
    /// {Fluent Interface}).  A value of `false` for the inherit schedule
    /// attribute indicates that a thread should *not* inherit the
    /// scheduling policy and priority of the thread that created it and
    /// instead should use the respective values supplied by this object;
    /// whereas a value of `true` indicates that the thread *should* inherit
    /// these attributes and ignore the respective values in this object.
    /// See @ref bslmt_threadutil  for information about support for this
    /// attribute.
    ThreadAttributes& setInheritSchedule(bool value);
 
    /// Set the value of the `schedulingPolicy` attribute of this object to
    /// the specified `value`.  Return a non-`const` reference to this
    /// object (see also {Fluent Interface}).  This attribute is ignored
    /// unless `inheritSchedule` is `false`.  See @ref bslmt_threadutil  for
    /// information about this attribute.
    ThreadAttributes& setSchedulingPolicy(SchedulingPolicy value);
 
    /// Set the `schedulingPriority` attribute of this object to the
    /// specified `value`.  Return a non-`const` reference to this object
    /// (see also {Fluent Interface}).  This attribute is ignored unless
    /// `inheritSchedule()` is `false`.  Higher values of `value` signify
    /// more urgent priorities.  Note that the valid range of priorities
    /// depends upon the platform and `schedulingPolicy` attribute, and the
    /// minimum and maximum priority values are determined by methods in
    /// @ref bslmt_threadutil .  See @ref bslmt_threadutil  for information about
    /// this attribute.
    ThreadAttributes& setSchedulingPriority(int value);
 
    /// Set the `stackSize` attribute of this object to the specified
    /// `value`.  Return a non-`const` reference to this object (see also
    /// {Fluent Interface}).  If `stackSize` is `e_UNSET_STACK_SIZE`, thread
    /// creation should use the default stack size value provided by
    /// @ref bslmt_configuration .  The behavior is undefined unless
    /// `e_UNSET_STACK_SIZE == stackSize` or `0 <= stackSize`.
    ThreadAttributes& setStackSize(int value);
 
    /// Set the `threadName` attribute of this object to the specified
    /// `value`.  Return a non-`const` reference to this object (see also
    /// {Fluent Interface}).
    ThreadAttributes& setThreadName(const bslstl::StringRef& value);
 
    // ACCESSORS
 
    /// Return the value of the `detachedState` attribute of this object.  A
    /// value of `e_CREATE_JOINABLE` indicates that a thread must be joined
    /// after it terminates to clean up its resources; a value of
    /// `e_CREATE_DETACHED` (the only other legal value) indicates that the
    /// resources will be cleaned up automatically upon thread termination,
    /// and that the thread must not be joined.
    DetachedState detachedState() const;
 
    /// Return the value of the `guardSize` attribute of this object.  The
    /// value `e_UNSET_GUARD_SIZE == guardSize` is intended to indicate that
    /// the default value as defined by the platform (which is typically the
    /// size of one or two pages) should be obtained from
    /// @ref bslmt_configuration  and used.
    int guardSize() const;
 
    /// Return the value of the `inheritSchedule` attribute of this object.
    /// A value of `false` for the inherit schedule attribute indicates that
    /// a thread should *not* inherit the scheduling policy and priority of
    /// the thread that created it and instead should use the respective
    /// values supplied by this object; whereas a value of `true` indicates
    /// that the thread *should* inherit these attributes and ignore the
    /// respective values in this object.  See @ref bslmt_threadutil  for
    /// information about support for this attribute.
    bool inheritSchedule() const;
 
    /// Format this object to the specified output `stream` at the (absolute
    /// value of) the optionally specified indentation `level` and return a
    /// reference to `stream`.  If `level` is specified, optionally specify
    /// `spacesPerLevel`, the number of spaces per indentation level for
    /// this and all of its nested objects.  If `level` is negative,
    /// suppress indentation of the first line.  If `spacesPerLevel` is
    /// negative format the entire output on one line, suppressing all but
    /// the initial indentation (as governed by `level`).  If `stream` is
    /// not valid on entry, this operation has no effect.
    bsl::ostream& print(bsl::ostream& stream,
                        int           level          = 0,
                        int           spacesPerLevel = 4) const;
 
    /// Return the value of the `schedulingPolicy` attribute of this object.
    /// This attribute is ignored unless `inheritSchedule` is `false`.  See
    /// @ref bslmt_threadutil  for information about this attribute.
    SchedulingPolicy schedulingPolicy() const;
 
    /// Return the value of the `schedulingPriority` attribute of this
    /// object.  This attribute is ignored unless `inheritSchedule()` is
    /// `false`.  Higher values of `value` signify more urgent priorities.
    /// Note that the valid range of priorities depends upon the platform
    /// and `schedulingPolicy` attribute, and the minimum and maximum
    /// priority values are determined by methods in @ref bslmt_threadutil .
    /// See @ref bslmt_threadutil  for information about this attribute.
    int schedulingPriority() const;
 
    /// Return the value of the `stackSize` attribute of this object.  If
    /// `stackSize` is `e_UNSET_STACK_SIZE`, thread creation should use the
    /// default stack size value provided by @ref bslmt_configuration .
    int stackSize() const;
 
    /// Return the `threadName` attribute of this object.  Note that the
    /// returned string reference will be invalidated if `setThreadName` is
    /// subsequently called on this object.
    bslstl::StringRef threadName() const;
 
                                  // Aspects
 
    /// Return the allocator used by this object to supply memory.
    bslma::Allocator *allocator() const;
};
 
// FREE OPERATORS
 
/// Return `true` if the specified `lhs` and `rhs` objects have the same
/// value, and `false` otherwise.  Two `ThreadAttributes` objects have the
/// same value if the corresponding values of their `detachedState`,
/// `guardSize`, `inheritSchedule`, `schedulingPolicy`,
/// `schedulingPriority`, and `stackSize` attributes are the same.
bool operator==(const ThreadAttributes& lhs, const ThreadAttributes& rhs);
 
/// Return `true` if the specified `lhs` and `rhs` objects do not have the
/// same value, and `false` otherwise.  Two `baltzo::LocalTimeDescriptor`
/// objects do not have the same value if the corresponding values of their
/// `detachedState`, `guardSize`, `inheritSchedule`, `schedulingPolicy`,
/// `schedulingPriority`, and `stackSize` attributes are not the same.
bool operator!=(const ThreadAttributes& lhs, const ThreadAttributes& rhs);
 
// FREE OPERATORS
 
/// Write the value of the specified `object` object to the specified output
/// `stream` in a single-line format, and return a reference to `stream`.
/// If `stream` is not valid on entry, this operation has no effect.  Note
/// that this human-readable format is not fully specified, can change
/// without notice, and is logically equivalent to:
/// @code
/// print(stream, 0, -1);
/// @endcode
bsl::ostream& operator<<(bsl::ostream&           stream,
                         const ThreadAttributes& object);
 
// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================
 
                          // ----------------------
                          // class ThreadAttributes
                          // ----------------------
 
// MANIPULATORS
inline
ThreadAttributes& ThreadAttributes::setDetachedState(
                                         ThreadAttributes::DetachedState value)
{
    BSLS_ASSERT_SAFE(e_CREATE_DETACHED == value ||
                     e_CREATE_JOINABLE == value);
 
    d_detachedState = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setGuardSize(int value)
{
    BSLMF_ASSERT(-1 == e_UNSET_GUARD_SIZE);
 
    BSLS_ASSERT_SAFE(-1 <= value);
 
    d_guardSize = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setInheritSchedule(bool value)
{
    d_inheritScheduleFlag = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setSchedulingPolicy(
                                      ThreadAttributes::SchedulingPolicy value)
{
    BSLS_ASSERT_SAFE(e_SCHED_MIN <= (int) value);
    BSLS_ASSERT_SAFE(                   (int) value <= e_SCHED_MAX);
 
    d_schedulingPolicy = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setSchedulingPriority(int value)
{
    d_schedulingPriority = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setStackSize(int value)
{
    BSLMF_ASSERT(-1 == e_UNSET_STACK_SIZE);
 
    BSLS_ASSERT_SAFE(-1 <= value);
 
    d_stackSize = value;
 
    return *this;
}
 
inline
ThreadAttributes& ThreadAttributes::setThreadName(
                                                const bslstl::StringRef& value)
{
    d_threadName.assign(value);
 
    return *this;
}
 
// ACCESSORS
inline
ThreadAttributes::DetachedState ThreadAttributes::detachedState() const
{
    return d_detachedState;
}
 
inline
int ThreadAttributes::guardSize() const
{
    return d_guardSize;
}
 
inline
bool ThreadAttributes::inheritSchedule() const
{
    return d_inheritScheduleFlag;
}
 
inline
ThreadAttributes::SchedulingPolicy ThreadAttributes::schedulingPolicy() const
{
    return d_schedulingPolicy;
}
 
inline
int ThreadAttributes::schedulingPriority() const
{
    return d_schedulingPriority;
}
 
inline
int ThreadAttributes::stackSize() const
{
    return d_stackSize;
}
 
inline
bslstl::StringRef ThreadAttributes::threadName() const
{
    return d_threadName;
}
 
                                  // Aspects
 
inline
bslma::Allocator *ThreadAttributes::allocator() const
{
    return d_threadName.get_allocator().mechanism();
}
 
}  // close package namespace
 
// FREE OPERATORS
inline
bsl::ostream& bslmt::operator<<(bsl::ostream&                  stream,
                                const bslmt::ThreadAttributes& object)
{
    return object.print(stream, 0, -1);
}
 
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2020 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */