Guard_T.h

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// -*- C++ -*-

//==========================================================================
/**
 *  @file    Guard_T.h
 *
 *  $Id: Guard_T.h 80826 2008-03-04 14:51:23Z wotte $
 *
 *   Moved from Synch.h.
 *
 *  @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
 */
//==========================================================================

#ifndef ACE_GUARD_T_H
#define ACE_GUARD_T_H
#include /**/ "ace/pre.h"

#include "ace/Lock.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

#include "ace/Global_Macros.h"
#include "ace/OS_NS_Thread.h"

ACE_BEGIN_VERSIONED_NAMESPACE_DECL

/**
 * @class ACE_Guard
 *
 * @brief This data structure is meant to be used within a method or
 * function...  It performs automatic aquisition and release of
 * a parameterized synchronization object <ACE_LOCK>.
 *
 * The <ACE_LOCK> class given as an actual parameter must provide at
 * the very least the <acquire>, <tryacquire>, <release>, and
 * <remove> methods.
 */
template <class ACE_LOCK>
class ACE_Guard
{
public:

  // = Initialization and termination methods.
  ACE_Guard (ACE_LOCK &l);

  /// Implicitly and automatically acquire (or try to acquire) the
  /// lock.  If @a block is non-0 then <acquire> the <ACE_LOCK>, else
  /// <tryacquire> it.
  ACE_Guard (ACE_LOCK &l, int block);

  /// Initialise the guard without implicitly acquiring the lock. The
  /// <become_owner> parameter indicates whether the guard should release
  /// the lock implicitly on destruction. The <block> parameter is
  /// ignored and is used here to disambiguate with the preceding
  /// constructor.
  ACE_Guard (ACE_LOCK &l, int block, int become_owner);

  /// Implicitly release the lock.
  ~ACE_Guard (void);

  // = Lock accessors.

  /// Explicitly acquire the lock.
  int acquire (void);

  /// Conditionally acquire the lock (i.e., won't block).
  int tryacquire (void);

  /// Explicitly release the lock, but only if it is held!
  int release (void);

  /// Relinquish ownership of the lock so that it is not released
  /// implicitly in the destructor.
  void disown (void);

  // = Utility methods.
  /// 1 if locked, 0 if couldn't acquire the lock
  /// (errno will contain the reason for this).
  int locked (void) const;

  /// Explicitly remove the lock.
  int remove (void);

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.

protected:

  /// Helper, meant for subclass only.
  ACE_Guard (ACE_LOCK *lock): lock_ (lock) {}

  /// Pointer to the ACE_LOCK we're guarding.
  ACE_LOCK *lock_;

  /// Keeps track of whether we acquired the lock or failed.
  int owner_;

private:
  // = Prevent assignment and initialization.
  ACE_UNIMPLEMENTED_FUNC (void operator= (const ACE_Guard<ACE_LOCK> &))
  ACE_UNIMPLEMENTED_FUNC (ACE_Guard (const ACE_Guard<ACE_LOCK> &))
};

/**
 * @class ACE_Write_Guard
 *
 * @brief This class is similar to class ACE_Guard, though it
 * acquires/releases a write lock automatically (naturally, the
 * <ACE_LOCK> it is instantiated with must support the appropriate
 * API).
 */
template <class ACE_LOCK>
class ACE_Write_Guard : public ACE_Guard<ACE_LOCK>
{
public:
  // = Initialization method.

  /// Implicitly and automatically acquire a write lock.
  ACE_Write_Guard (ACE_LOCK &m);

  /// Implicitly and automatically acquire (or try to acquire) a write
  /// lock.
  ACE_Write_Guard (ACE_LOCK &m, int block);

  // = Lock accessors.

  /// Explicitly acquire the write lock.
  int acquire_write (void);

  /// Explicitly acquire the write lock.
  int acquire (void);

  /// Conditionally acquire the write lock (i.e., won't block).
  int tryacquire_write (void);

  /// Conditionally acquire the write lock (i.e., won't block).
  int tryacquire (void);

  // = Utility methods.

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};

/**
 * @class ACE_Read_Guard
 *
 * @brief This class is similar to class ACE_Guard, though it
 * acquires/releases a read lock automatically (naturally, the
 * <ACE_LOCK> it is instantiated with must support the appropriate
 * API).
 */
template <class ACE_LOCK>
class ACE_Read_Guard : public ACE_Guard<ACE_LOCK>
{
public:
  // = Initialization methods.

  /// Implicitly and automatically acquire a read lock.
  ACE_Read_Guard (ACE_LOCK& m);

  /// Implicitly and automatically acquire (or try to acquire) a read
  /// lock.
  ACE_Read_Guard (ACE_LOCK &m, int block);

  // = Lock accessors.

  /// Explicitly acquire the read lock.
  int acquire_read (void);

  /// Explicitly acquire the read lock.
  int acquire (void);

  /// Conditionally acquire the read lock (i.e., won't block).
  int tryacquire_read (void);

  /// Conditionally acquire the read lock (i.e., won't block).
  int tryacquire (void);

  // = Utility methods.

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};

#if !(defined (ACE_HAS_THREADS) && (defined (ACE_HAS_THREAD_SPECIFIC_STORAGE) || defined (ACE_HAS_TSS_EMULATION)))

#define ACE_TSS_Guard ACE_Guard
#define ACE_TSS_Write_GUARD ACE_Write_Guard
#define ACE_TSS_Read_GUARD ACE_Read_Guard

#else
 /* ACE platform supports some form of threading and
  thread-specific storage. */

/**
 * @class ACE_TSS_Guard
 *
 * @brief This data structure is meant to be used within a method or
 * function...  It performs automatic aquisition and release of
 * a synchronization object.  Moreover, it ensures that the lock
 * is released even if a thread exits via <thr_exit>!
 */
template <class ACE_LOCK>
class ACE_TSS_Guard
{
public:
  // = Initialization and termination methods.

  /// Implicitly and automatically acquire the thread-specific lock.
  ACE_TSS_Guard (ACE_LOCK &lock, int block = 1);

  /// Implicitly release the thread-specific lock.
  ~ACE_TSS_Guard (void);

  // = Lock accessors.

  /// Explicitly acquire the thread-specific lock.
  int acquire (void);

  /// Conditionally acquire the thread-specific lock (i.e., won't
  /// block).
  int tryacquire (void);

  /// Explicitly release the thread-specific lock.
  int release (void);

  // = Utility methods.
  /// Explicitly release the thread-specific lock.
  int remove (void);

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.

protected:
  /// Helper, meant for subclass only.
  ACE_TSS_Guard (void);

  /// Initialize the key.
  void init_key (void);

  /// Called when thread exits to clean up the lock.
  static void cleanup (void *ptr);

  /// Thread-specific key...
  ACE_thread_key_t key_;

private:
  // = Prevent assignment and initialization.
  ACE_UNIMPLEMENTED_FUNC (void operator= (const ACE_TSS_Guard<ACE_LOCK> &))
  ACE_UNIMPLEMENTED_FUNC (ACE_TSS_Guard (const ACE_TSS_Guard<ACE_LOCK> &))
};

/**
 * @class ACE_TSS_Write_Guard
 *
 * @brief This class is similar to class ACE_TSS_Guard, though it
 * acquires/releases a write-lock automatically (naturally, the
 * ACE_LOCK it is instantiated with must support the appropriate
 * API).
 */
template <class ACE_LOCK>
class ACE_TSS_Write_Guard : public ACE_TSS_Guard<ACE_LOCK>
{
public:
  // = Initialization method.

  /// Implicitly and automatically acquire the thread-specific write lock.
  ACE_TSS_Write_Guard (ACE_LOCK &lock, int block = 1);

  // = Lock accessors.

  /// Explicitly acquire the thread-specific write lock.
  int acquire_write (void);

  /// Explicitly acquire the thread-specific write lock.
  int acquire (void);

  /// Conditionally acquire the thread-specific write lock (i.e., won't block).
  int tryacquire_write (void);

  /// Conditionally acquire the thread-specific write lock (i.e., won't block).
  int tryacquire (void);

  // = Utility methods.

  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};

/**
 * @class ACE_TSS_Read_Guard
 *
 * @brief This class is similar to class <ACE_TSS_Guard>, though it
 * acquires/releases a read lock automatically (naturally, the
 * <ACE_LOCK> it is instantiated with must support the
 * appropriate API).
 */
template <class ACE_LOCK>
class ACE_TSS_Read_Guard : public ACE_TSS_Guard<ACE_LOCK>
{
public:
  // = Initialization method.
  /// Implicitly and automatically acquire the thread-specific read lock.
  ACE_TSS_Read_Guard (ACE_LOCK &lock, int block = 1);

  // = Lock accessors.
  /// Explicitly acquire the thread-specific read lock.
  int acquire_read (void);

  /// Explicitly acquire the thread-specific read lock.
  int acquire (void);

  /// Conditionally acquire the thread-specific read lock (i.e., won't
  /// block).
  int tryacquire_read (void);

  /// Conditionally acquire the thread-specific read lock (i.e., won't
  /// block).
  int tryacquire (void);

  // = Utility methods.
  /// Dump the state of an object.
  void dump (void) const;

  // ACE_ALLOC_HOOK_DECLARE;
  // Declare the dynamic allocation hooks.
};

#endif /* !(defined (ACE_HAS_THREADS) && (defined (ACE_HAS_THREAD_SPECIFIC_STORAGE) || defined (ACE_HAS_TSS_EMULATION))) */

ACE_END_VERSIONED_NAMESPACE_DECL

#if defined (__ACE_INLINE__)
#include "ace/Guard_T.inl"
#endif /* __ACE_INLINE__ */

#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "ace/Guard_T.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */

#if defined (ACE_TEMPLATES_REQUIRE_PRAGMA)
#pragma implementation ("Guard_T.cpp")
#endif /* ACE_TEMPLATES_REQUIRE_PRAGMA */

#include /**/ "ace/post.h"
#endif /* ACE_GUARD_T_H */

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