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# ACE_Lock Class Reference

This is the abstract base class that contains the uniform locking API that is supported by all the ACE synchronization mechanisms. More...

`#include <Synch.h>`

Inheritance diagram for ACE_Lock:

[legend]
List of all members.

## Public Methods
| ACE_Lock (void)
| CE needs a default ctor here. More...
virtual | ~ACE_Lock (void)
| Noop virtual destructor. More...
virtual int | remove (void)=0
virtual int | acquire (void)=0
| Block the thread until the lock is acquired. Returns -1 on failure. More...
virtual int | tryacquire (void)=0
virtual int | release (void)=0
| Release the lock. Returns -1 on failure. More...
virtual int | acquire_read (void)=0
virtual int | acquire_write (void)=0
virtual int | tryacquire_read (void)=0
virtual int | tryacquire_write (void)=0
virtual int | tryacquire_write_upgrade (void)=0

## Detailed Description

This is the abstract base class that contains the uniform locking API that is supported by all the ACE synchronization mechanisms.

This class is typically used in conjunction with the <ACE_Lock_Adapter> in order to provide a polymorphic interface to the ACE synchronization mechanisms (e.g., <ACE_Mutex>, <ACE_Semaphore>, <ACE_RW_Mutex>, etc). Note that the reason that all of ACE doesn't use polymorphic locks is that (1) they add ~20% extra overhead for virtual function calls and (2) objects with virtual functions can't be placed into shared memory.

## Constructor & Destructor Documentation

ACE_INLINE ACE_Lock::ACE_Lock | ( | void |  | ) |

| CE needs a default ctor here.

ACE_Lock::~ACE_Lock | ( | void |  | ) | `[virtual]`

| Noop virtual destructor.

## Member Function Documentation

virtual int ACE_Lock::acquire | ( | void |  | ) | `[pure virtual]`

| Block the thread until the lock is acquired. Returns -1 on failure. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::acquire_read | ( | void |  | ) | `[pure virtual]`

| Block until the thread acquires a read lock. If the locking mechanism doesn't support read locks then this just calls <acquire>. Returns -1 on failure. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::acquire_write | ( | void |  | ) | `[pure virtual]`

| Block until the thread acquires a write lock. If the locking mechanism doesn't support read locks then this just calls <acquire>. Returns -1 on failure. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::release | ( | void |  | ) | `[pure virtual]`

| Release the lock. Returns -1 on failure. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::remove | ( | void |  | ) | `[pure virtual]`

| Explicitly destroy the lock. Note that only one thread should call this method since it doesn't protect against race conditions. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::tryacquire | ( | void |  | ) | `[pure virtual]`

| Conditionally acquire the lock (i.e., won't block). Returns -1 on failure. If we "failed" because someone else already had the lock, <errno> is set to <EBUSY>. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::tryacquire_read | ( | void |  | ) | `[pure virtual]`

| Conditionally acquire a read lock. If the locking mechanism doesn't support read locks then this just calls <acquire>. Returns -1 on failure. If we "failed" because someone else already had the lock, <errno> is set to <EBUSY>. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::tryacquire_write | ( | void |  | ) | `[pure virtual]`

| Conditionally acquire a write lock. If the locking mechanism doesn't support read locks then this just calls <acquire>. Returns -1 on failure. If we "failed" because someone else already had the lock, <errno> is set to <EBUSY>. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

virtual int ACE_Lock::tryacquire_write_upgrade | ( | void |  | ) | `[pure virtual]`

| Conditionally try to upgrade a lock held for read to a write lock. If the locking mechanism doesn't support read locks then this just calls <acquire>. Returns 0 on success, -1 on failure. Reimplemented in ACE_Adaptive_Lock, ACE_Lock_Adapter, ACE_Reverse_Lock, ACE_Lock_Adapter< ACE_SELECT_REACTOR_TOKEN >, ACE_Lock_Adapter< ACE_Process_Mutex >, ACE_Lock_Adapter< ACE_SYNCH_MUTEX >, ACE_Lock_Adapter< ACE_Select_Reactor_Token >, and ACE_Reverse_Lock< MUTEX >.

The documentation for this class was generated from the following files:

- Synch.h
- Synch.cpp
- Synch.i