#include <Synch.h>
Public Methods | |
ACE_Null_Semaphore (u_int count=1, int type=USYNC_THREAD, const ACE_TCHAR *name=0, void *=0, int max=0x7fffffff) | |
~ACE_Null_Semaphore (void) | |
int | remove (void) |
Return 0. | |
int | acquire (void) |
Return 0. | |
int | acquire (ACE_Time_Value &) |
Return -1 with <errno> == <ETIME>. | |
int | acquire (ACE_Time_Value *) |
Return -1 with <errno> == <ETIME>. | |
int | tryacquire (void) |
Return 0. | |
int | release (void) |
Return 0. | |
int | release (size_t) |
Return 0. | |
int | acquire_write (void) |
Return 0. | |
int | tryacquire_write (void) |
Return 0. | |
int | tryacquire_write_upgrade (void) |
Return 0. | |
int | acquire_read (void) |
Return 0. | |
int | tryacquire_read (void) |
Return 0. | |
void | dump (void) const |
Dump the state of an object. | |
Public Attributes | |
ACE_ALLOC_HOOK_DECLARE | |
Declare the dynamic allocation hooks. |
Although the methods are no-ops, the return values are different for the blocking as opposed to timed acquires. The blocking version of acquire() is often used to serialize access to a critical section, whereas the timed version is often used to wait for another thread to update some condition or change some shared state. When using an ACE_Null_Semaphore, however, there's no other thread involved to change a state or condition (otherwise, a null semaphore would be inappropriate). Returning an error value signifies that the state or condition has not been (and can't be) changed, which is consistent with the behavior of the threaded case where a timeout occurs before the state or condition is changed.
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Return -1 with <errno> == <ETIME>.
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Return -1 with <errno> == <ETIME>.
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Return 0.
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Return 0.
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Return 0.
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Dump the state of an object.
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Return 0.
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Return 0.
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Return 0.
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Return 0.
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Return 0.
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Return 0.
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Return 0.
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Declare the dynamic allocation hooks.
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