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Hazelcast C++ Client
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Hazelcast C++ Client
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ISemaphore is a backed-up distributed alternative to the java.util.concurrent.Semaphore. More...
#include <ISemaphore.h>
Inheritance diagram for hazelcast::client::ISemaphore:Public Member Functions | |
| bool | init (int permits) |
| Try to initialize this ISemaphore instance with given permit count. More... | |
| void | acquire () |
| Acquires a permit, if one is available and returns immediately, reducing the number of available permits by one. More... | |
| void | acquire (int permits) |
| Acquires the given number of permits, if they are available, and returns immediately, reducing the number of available permits by the given amount. More... | |
| int | availablePermits () |
| Returns the current number of permits currently available in this semaphore. More... | |
| int | drainPermits () |
| Acquires and returns all permits that are immediately available. More... | |
| void | reducePermits (int reduction) |
| Shrinks the number of available permits by the indicated reduction. More... | |
| void | release () |
| Releases a permit, increasing the number of available permits by one. More... | |
| void | release (int permits) |
| Releases the given number of permits, increasing the number of available permits by that amount. More... | |
| bool | tryAcquire () |
| Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one. More... | |
| bool | tryAcquire (int permits) |
| Acquires the given number of permits, if they are available, and returns immediately, with the value true, reducing the number of available permits by the given amount. More... | |
| bool | tryAcquire (long timeoutInMillis) |
| Acquires a permit from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted. More... | |
| bool | tryAcquire (int permits, long timeoutInMillis) |
| Acquires the given number of permits, if they are available and returns immediately, with the value true, reducing the number of available permits by the given amount. More... | |
Friends | |
| class | HazelcastClient |
ISemaphore is a backed-up distributed alternative to the java.util.concurrent.Semaphore.
ISemaphore is a cluster-wide counting semaphore. Conceptually, it maintains a set of permits. Each acquire() blocks if necessary until a permit is available, and then takes it. Each release() adds a permit, potentially releasing a blocking acquirer. However, no actual permit objects are used; the semaphore just keeps a count of the number available and acts according ly. The Hazelcast distributed semaphore implementation guarantees that threads invoking any of the acquire methods are selected to obtain permits in the order in which their invocation of those methods was processed(first-in-first-out; FIFO). Note that FIFO ordering necessarily applies to specific internal points of execution within the cluster. So, it is possible for one member to invoke acquire before another, but reach the ordering point after the other, and similarly upon return from the method.
This class also provides convenience methods to acquire and release(int) release multiple permits at a time. Beware of the increased risk of indefinite postponement when using the multiple acquire. If a single permit is released to a semaphore that is currently blocking, a thread waiting for one permit will acquire it before a thread waiting for multiple permits regardless of the call order.
Correct usage of a semaphore is established by programming convention in the application.
| void hazelcast::client::ISemaphore::acquire | ( | ) |
Acquires a permit, if one is available and returns immediately, reducing the number of available permits by one.
If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:
Some other thread invokes one of the release methods for this semaphore and the current thread is next to be assigned a permit; This ISemaphore instance is destroyed; or Some other thread interrupts the current thread.
If the current thread:
has its interrupted status set on entry to this method; or is interrupted while waiting for a permit,
then InterruptedException is thrown and the current thread's interrupted status is cleared.
| InterruptedException | if the current thread is interrupted |
| IllegalStateException | if hazelcast instance is shutdown while waiting |
| void hazelcast::client::ISemaphore::acquire | ( | int | permits | ) |
Acquires the given number of permits, if they are available, and returns immediately, reducing the number of available permits by the given amount.
If insufficient permits are available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:
Some other thread invokes one of the release() release methods for this semaphore, the current thread is next to be assigned permits and the number of available permits satisfies this request; This ISemaphore instance is destroyed; or Some other thread interrupts the current thread.
If the current thread:
has its interrupted status set on entry to this method; or is interrupted while waiting for a permit,
then InterruptedException is thrown and the current thread's interrupted status is cleared.
| permits | the number of permits to acquire |
| InterruptedException | if the current thread is interrupted |
| IllegalStateException | if hazelcast instance is shutdown while waiting |
| int hazelcast::client::ISemaphore::availablePermits | ( | ) |
Returns the current number of permits currently available in this semaphore.
This method is typically used for debugging and testing purposes.
| int hazelcast::client::ISemaphore::drainPermits | ( | ) |
Acquires and returns all permits that are immediately available.
| bool hazelcast::client::ISemaphore::init | ( | int | permits | ) |
Try to initialize this ISemaphore instance with given permit count.
| void hazelcast::client::ISemaphore::reducePermits | ( | int | reduction | ) |
Shrinks the number of available permits by the indicated reduction.
This method differs from acquire in that it does not block waiting for permits to become available.
| reduction | the number of permits to remove |
| IllegalArgumentException | if reduction is negative |
| void hazelcast::client::ISemaphore::release | ( | ) |
Releases a permit, increasing the number of available permits by one.
If any threads in the cluster are trying to acquire a permit, then one is selected and given the permit that was just released.
There is no requirement that a thread that releases a permit must have acquired that permit by calling one of the acquire() acquire methods. Correct usage of a semaphore is established by programming convention in the application.
| void hazelcast::client::ISemaphore::release | ( | int | permits | ) |
Releases the given number of permits, increasing the number of available permits by that amount.
There is no requirement that a thread that releases a permit must have acquired that permit by calling one of the acquire() acquire methods. Correct usage of a semaphore is established by programming convention in the application.
| permits | the number of permits to release |
| bool hazelcast::client::ISemaphore::tryAcquire | ( | ) |
Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.
If no permit is available then this method will return immediately with the value false.
| bool hazelcast::client::ISemaphore::tryAcquire | ( | int | permits | ) |
Acquires the given number of permits, if they are available, and returns immediately, with the value true, reducing the number of available permits by the given amount.
If insufficient permits are available then this method will return immediately with the value false and the number of available permits is unchanged.
| permits | the number of permits to acquire |
| bool hazelcast::client::ISemaphore::tryAcquire | ( | long | timeoutInMillis | ) |
Acquires a permit from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted.
Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.
If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:
Some other thread invokes the release method for this semaphore and the current thread is next to be assigned a permit; or Some other thread interrupts the current thread; or The specified waiting time elapses.
If a permit is acquired then the value true is returned.
If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.
If the current thread:
has its interrupted status set on entry to this method; or is interrupted while waiting for a permit,
then InterruptedException is thrown and the current thread's interrupted status is cleared.
| timeoutInMillis | the maximum time to wait for a permit |
| InterruptedException | if the current thread is interrupted |
| IllegalStateException | if hazelcast instance is shutdown while waiting |
| bool hazelcast::client::ISemaphore::tryAcquire | ( | int | permits, |
| long | timeoutInMillis | ||
| ) |
Acquires the given number of permits, if they are available and returns immediately, with the value true, reducing the number of available permits by the given amount.
If insufficient permits are available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:
Some other thread invokes one of the release() release methods for this semaphore, the current thread is next to be assigned permits and the number of available permits satisfies this request; or Some other thread interrupts the current thread; or The specified waiting time elapses.
If the permits are acquired then the value true is returned.
If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.
If the current thread:
has its interrupted status set on entry to this method; or is interrupted while waiting for a permit,
then InterruptedException is thrown and the current thread's interrupted status is cleared.
| permits | the number of permits to acquire |
| timeoutInMillis | the maximum time to wait for the permits |
| InterruptedException | if the current thread is interrupted |
| IllegalStateException | if hazelcast instance is shutdown while waiting |
1.8.6
