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// -*- C++ -*-
//==========================================================================
/**
* @file Recursive_Thread_Mutex.h
*
* @author Douglas C. Schmidt <d.schmidt@vanderbilt.edu> and
* Abdullah Sowayan <abdullah.sowayan@lmco.com>
*/
//==========================================================================
#ifndef ACE_RECURSIVE_THREAD_MUTEX_H
#define ACE_RECURSIVE_THREAD_MUTEX_H
#include /**/ "ace/pre.h"
#include /**/ "ace/ACE_export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#if !defined (ACE_HAS_THREADS)
# include "ace/Null_Mutex.h"
#else /* ACE_HAS_THREADS */
// ACE platform supports some form of threading.
#include "ace/OS_NS_Thread.h"
ACE_BEGIN_VERSIONED_NAMESPACE_DECL
/**
* @class ACE_Recursive_Thread_Mutex
*
* @brief Implement a C++ wrapper that allows nested acquisition and
* release of a mutex that occurs in the same thread.
*/
class ACE_Export ACE_Recursive_Thread_Mutex
{
public:
/// Initialize a recursive mutex.
ACE_Recursive_Thread_Mutex (const ACE_TCHAR *name = 0,
ACE_mutexattr_t *arg = 0);
/// Implicitly release a recursive mutex.
~ACE_Recursive_Thread_Mutex ();
/**
* Implicitly release a recursive mutex. Note that only one thread
* should call this method since it doesn't protect against race
* conditions.
*/
int remove ();
/**
* Acquire a recursive mutex (will increment the nesting level and
* not deadmutex if the owner of the mutex calls this method more
* than once).
*/
int acquire ();
/**
* Block the thread until we acquire the mutex or until @a tv times
* out, in which case -1 is returned with @c errno == @c ETIME. Note
* that @a tv is assumed to be in "absolute" rather than "relative"
* time. The value of @a tv is updated upon return to show the
* actual (absolute) acquisition time.
*/
int acquire (ACE_Time_Value &tv);
/**
* If @a tv == 0 the call acquire() directly. Otherwise, Block the
* thread until we acquire the mutex or until @a tv times out, in
* which case -1 is returned with @c errno == @c ETIME. Note that
* <*tv> is assumed to be in "absolute" rather than "relative" time.
* The value of <*tv> is updated upon return to show the actual
* (absolute) acquisition time.
*/
int acquire (ACE_Time_Value *tv);
/**
* Conditionally acquire a recursive mutex (i.e., won't block).
* Returns -1 on failure. If we "failed" because someone else
* already had the lock, @c errno is set to @c EBUSY.
*/
int tryacquire ();
/**
* Acquire mutex ownership. This calls acquire() and is only
* here to make the ACE_Recusive_Thread_Mutex interface consistent
* with the other synchronization APIs.
*/
int acquire_read ();
/**
* Acquire mutex ownership. This calls acquire() and is only
* here to make the ACE_Recusive_Thread_Mutex interface consistent
* with the other synchronization APIs.
*/
int acquire_write ();
/**
* Conditionally acquire mutex (i.e., won't block). This calls
* tryacquire() and is only here to make the
* ACE_Recusive_Thread_Mutex interface consistent with the other
* synchronization APIs. Returns -1 on failure. If we "failed"
* because someone else already had the lock, @c errno is set to
* @c EBUSY.
*/
int tryacquire_read ();
/**
* Conditionally acquire mutex (i.e., won't block). This calls
* tryacquire() and is only here to make the
* ACE_Recusive_Thread_Mutex interface consistent with the other
* synchronization APIs. Returns -1 on failure. If we "failed"
* because someone else already had the lock, @c errno is set to
* @c EBUSY.
*/
int tryacquire_write ();
/**
* This is only here to make the ACE_Recursive_Thread_Mutex
* interface consistent with the other synchronization APIs.
* Assumes the caller has already acquired the mutex using one of
* the above calls, and returns 0 (success) always.
*/
int tryacquire_write_upgrade ();
/**
* Releases a recursive mutex (will not release mutex until all the
* nesting level drops to 0, which means the mutex is no longer
* held).
*/
int release ();
/// Return the id of the thread that currently owns the mutex.
ACE_thread_t get_thread_id ();
/**
* Return the nesting level of the recursion. When a thread has
* acquired the mutex for the first time, the nesting level == 1.
* The nesting level is incremented every time the thread acquires
* the mutex recursively. Note that if the ACE_HAS_RECURSIVE_MUTEXES
* macro is enabled then this method may return -1 on platforms that
* do not expose the internal count.
*/
int get_nesting_level ();
/// Returns a reference to the recursive mutex;
ACE_recursive_thread_mutex_t &lock ();
/// Returns a reference to the recursive mutex's internal mutex;
ACE_thread_mutex_t &get_nesting_mutex ();
/// Dump the state of an object.
void dump () const;
/// Declare the dynamic allocation hooks.
ACE_ALLOC_HOOK_DECLARE;
protected:
// = This method should *not* be public (they hold no locks...)
void set_thread_id (ACE_thread_t t);
/// Recursive mutex.
ACE_recursive_thread_mutex_t lock_;
/// Keeps track of whether remove() has been called yet to avoid
/// multiple remove() calls, e.g., explicitly and implicitly in the
/// destructor. This flag isn't protected by a lock, so make sure
/// that you don't have multiple threads simultaneously calling
/// remove() on the same object, which is a bad idea anyway...
bool removed_;
private:
void operator= (const ACE_Recursive_Thread_Mutex &) = delete;
ACE_Recursive_Thread_Mutex (const ACE_Recursive_Thread_Mutex &) = delete;
};
ACE_END_VERSIONED_NAMESPACE_DECL
#if defined (__ACE_INLINE__)
#include "ace/Recursive_Thread_Mutex.inl"
#endif /* __ACE_INLINE__ */
#endif /* !ACE_HAS_THREADS */
#include /**/ "ace/post.h"
#endif /* ACE_RECURSIVE_THREAD_MUTEX_H */
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