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Diffstat (limited to 'libparc/parc/concurrent/parc_FutureTask.h')
| -rwxr-xr-x | libparc/parc/concurrent/parc_FutureTask.h | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/libparc/parc/concurrent/parc_FutureTask.h b/libparc/parc/concurrent/parc_FutureTask.h new file mode 100755 index 00000000..9a5776c5 --- /dev/null +++ b/libparc/parc/concurrent/parc_FutureTask.h @@ -0,0 +1,657 @@ +/* + * Copyright (c) 2017 Cisco and/or its affiliates. + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +/** + * @file parc_FutureTask.h + * @ingroup threading + * @brief An encapsulated, asynchronous computation. + * + * This type associates a function and a pointer to data and provides the functionality + * to invoke the function supplying the given pointer to data and returning the result. + * + * The operations of invoking the function and collecting its return value may be asynchronous from each other + * in that an attempting to fetch the return value before the function has been invoked + * will cause the calling thread to block until the function has been invoked and run to completion. + * This enables the use of PARCFutureTask in a work queue, or thread pool where tasks are run asynchronously + * from each other and from an originating thread. + * + * Each instance of the type may be cancelled, + * inhibiting a future invocation of the associated function. + * + * Typical use is a one time invocation of the associated function, induced by the `parcFutureTask_Get`, + * but invoking `parcFutureTask_GetAndReset` invokes the associated function and resets the task to the initial state, + * permitting a future call to `parcFutureTask_Get` or `parcFutureTask_GetAndReset` the run the associated function again. + * + */ +#ifndef PARCLibrary_parc_FutureTask +#define PARCLibrary_parc_FutureTask +#include <stdbool.h> +#include <stdint.h> + +#include <parc/algol/parc_JSON.h> +#include <parc/algol/parc_HashCode.h> +#include <parc/concurrent/parc_Timeout.h> +#include <parc/algol/parc_Execution.h> + +struct PARCFutureTask; +typedef struct PARCFutureTask PARCFutureTask; + +typedef struct PARCFutureTaskResult { + void *value; + PARCExecution *execution; +} PARCFutureTaskResult; + +/** + * Increase the number of references to a `PARCFutureTask` instance. + * + * Note that new `PARCFutureTask` is not created, + * only that the given `PARCFutureTask` reference count is incremented. + * Discard the reference by invoking `parcFutureTask_Release`. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * @return The same value as @p instance. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * PARCFutureTask *b = parcFutureTask_Acquire(); + * + * parcFutureTask_Release(&a); + * parcFutureTask_Release(&b); + * } + * @endcode + */ +PARCFutureTask *parcFutureTask_Acquire(const PARCFutureTask *instance); + +#ifdef PARCLibrary_DISABLE_VALIDATION +# define parcFutureTask_OptionalAssertValid(_instance_) +#else +# define parcFutureTask_OptionalAssertValid(_instance_) parcFutureTask_AssertValid(_instance_) +#endif + +/** + * Assert that the given `PARCFutureTask` instance is valid. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * parcFutureTask_AssertValid(a); + * + * printf("Instance is valid.\n"); + * + * parcFutureTask_Release(&b); + * } + * @endcode + */ +void parcFutureTask_AssertValid(const PARCFutureTask *instance); + +/** + * Create an instance of `PARCFutureTask` + * + * If the parameter is an instance of `PARCObject` a reference to the object will + * be created and ultimately released via `parcFutureTask_Release` + * + * @param [in] function A pointer to a function to call. + * @param [in] parameter A pointer that will be passed to the function when invoked. + * + * @return non-NULL A pointer to a valid `PARCFutureTask` instance. + * @return NULL An error occurred. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(function, parameter); + * + * parcFutureTask_Release(&a); + * } + * @endcode + */ +PARCFutureTask *parcFutureTask_Create(void *(*runnable)(PARCFutureTask *task, void *parameter), void *parameter); + +/** + * Compares @p instance with @p other for order. + * + * Returns a negative integer, zero, or a positive integer as @p instance + * is less than, equal to, or greater than @p other. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * @param [in] other A pointer to a valid PARCFutureTask instance. + * + * @return <0 Instance is less than @p other. + * @return 0 Instance a and instance b compare the same. + * @return >0 Instance a is greater than instance b. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * PARCFutureTask *b = parcFutureTask_Create(); + * + * if (parcFutureTask_Compare(a, b) == 0) { + * printf("Instances are equal.\n"); + * } + * + * parcFutureTask_Release(&a); + * parcFutureTask_Release(&b); + * } + * @endcode + * + * @see parcFutureTask_Equals + */ +int parcFutureTask_Compare(const PARCFutureTask *instance, const PARCFutureTask *other); + +/** + * Create an independent copy the given `PARCBuffer` + * + * A new buffer is created as a complete copy of the original. + * + * @param [in] original A pointer to a valid PARCFutureTask instance. + * + * @return NULL Memory could not be allocated. + * @return non-NULL A pointer to a new `PARCFutureTask` instance. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * PARCFutureTask *copy = parcFutureTask_Copy(&b); + * + * parcFutureTask_Release(&b); + * parcFutureTask_Release(©); + * } + * @endcode + */ +PARCFutureTask *parcFutureTask_Copy(const PARCFutureTask *original); + +/** + * Print a human readable representation of the given `PARCFutureTask`. + * + * @param [in] instance A pointer to a valid `PARCFutureTask` instance. + * @param [in] indentation The indentation level to use for printing. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * parcFutureTask_Display(a, 0); + * + * parcFutureTask_Release(&a); + * } + * @endcode + */ +void parcFutureTask_Display(const PARCFutureTask *instance, int indentation); + +/** + * Determine if two `PARCFutureTask` instances are equal. + * + * The following equivalence relations on non-null `PARCFutureTask` instances are maintained: * + * * It is reflexive: for any non-null reference value x, `parcFutureTask_Equals(x, x)` must return true. + * + * * It is symmetric: for any non-null reference values x and y, `parcFutureTask_Equals(x, y)` must return true if and only if + * `parcFutureTask_Equals(y x)` returns true. + * + * * It is transitive: for any non-null reference values x, y, and z, if + * `parcFutureTask_Equals(x, y)` returns true and + * `parcFutureTask_Equals(y, z)` returns true, + * then `parcFutureTask_Equals(x, z)` must return true. + * + * * It is consistent: for any non-null reference values x and y, multiple invocations of `parcFutureTask_Equals(x, y)` + * consistently return true or consistently return false. + * + * * For any non-null reference value x, `parcFutureTask_Equals(x, NULL)` must return false. + * + * @param [in] x A pointer to a valid PARCFutureTask instance. + * @param [in] y A pointer to a valid PARCFutureTask instance. + * + * @return true The instances x and y are equal. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * PARCFutureTask *b = parcFutureTask_Create(); + * + * if (parcFutureTask_Equals(a, b)) { + * printf("Instances are equal.\n"); + * } + * + * parcFutureTask_Release(&a); + * parcFutureTask_Release(&b); + * } + * @endcode + * @see parcFutureTask_HashCode + */ +bool parcFutureTask_Equals(const PARCFutureTask *x, const PARCFutureTask *y); + +/** + * Returns a hash code value for the given instance. + * + * The general contract of `HashCode` is: + * + * Whenever it is invoked on the same instance more than once during an execution of an application, + * the `HashCode` function must consistently return the same value, + * provided no information used in a corresponding comparisons on the instance is modified. + * + * This value need not remain consistent from one execution of an application to another execution of the same application. + * If two instances are equal according to the {@link parcFutureTask_Equals} method, + * then calling the {@link parcFutureTask_HashCode} method on each of the two instances must produce the same integer result. + * + * It is not required that if two instances are unequal according to the + * {@link parcFutureTask_Equals} function, + * then calling the `parcFutureTask_HashCode` + * method on each of the two objects must produce distinct integer results. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * @return The hashcode for the given instance. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * PARCHashCode hashValue = parcFutureTask_HashCode(buffer); + * parcFutureTask_Release(&a); + * } + * @endcode + */ +PARCHashCode parcFutureTask_HashCode(const PARCFutureTask *instance); + +/** + * Determine if an instance of `PARCFutureTask` is valid. + * + * Valid means the internal state of the type is consistent with its required current or future behaviour. + * This may include the validation of internal instances of types. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * @return true The instance is valid. + * @return false The instance is not valid. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * if (parcFutureTask_IsValid(a)) { + * printf("Instance is valid.\n"); + * } + * + * parcFutureTask_Release(&a); + * } + * @endcode + * + */ +bool parcFutureTask_IsValid(const PARCFutureTask *instance); + +/** + * Release a previously acquired reference to the given `PARCFutureTask` instance, + * decrementing the reference count for the instance. + * + * The pointer to the instance is set to NULL as a side-effect of this function. + * + * If the invocation causes the last reference to the instance to be released, + * the instance is deallocated and the instance's implementation will perform + * additional cleanup and release other privately held references. + * + * @param [in,out] instancePtr A pointer to a pointer to the instance to release. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * parcFutureTask_Release(&a); + * } + * @endcode + */ +void parcFutureTask_Release(PARCFutureTask **instancePtr); + +/** + * Create a `PARCJSON` instance (representation) of the given object. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * @return NULL Memory could not be allocated to contain the `PARCJSON` instance. + * @return non-NULL An allocated C string that must be deallocated via parcMemory_Deallocate(). + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * PARCJSON *json = parcFutureTask_ToJSON(a); + * + * printf("JSON representation: %s\n", parcJSON_ToString(json)); + * parcJSON_Release(&json); + * + * parcFutureTask_Release(&a); + * } + * @endcode + */ +PARCJSON *parcFutureTask_ToJSON(const PARCFutureTask *instance); + +/** + * Produce a null-terminated string representation of the specified `PARCFutureTask`. + * + * The result must be freed by the caller via {@link parcMemory_Deallocate}. + * + * @param [in] instance A pointer to a valid PARCFutureTask instance. + * + * @return NULL Cannot allocate memory. + * @return non-NULL A pointer to an allocated, null-terminated C string that must be deallocated via {@link parcMemory_Deallocate}. + * + * Example: + * @code + * { + * PARCFutureTask *a = parcFutureTask_Create(); + * + * char *string = parcFutureTask_ToString(a); + * + * parcFutureTask_Release(&a); + * + * parcMemory_Deallocate(&string); + * } + * @endcode + * + * @see parcFutureTask_Display + */ +char *parcFutureTask_ToString(const PARCFutureTask *instance); + +/** + * Wakes up a single thread that is waiting on this object (see `parcFutureTask_Wait)`. + * If any threads are waiting on this object, one of them is chosen to be awakened. + * The choice is arbitrary and occurs at the discretion of the underlying implementation. + * + * The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. + * The awakened thread will compete in the usual manner with any other threads that might be actively + * competing to synchronize on this object; + * for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object. + * + * @param [in] object A pointer to a valid PARCFutureTask instance. + * + * Example: + * @code + * { + * if (parcFutureTask_Lock(object)) { + * parcFutureTask_Notify(object); + * parcFutureTask_Unlock(object); + * } + * } + * @endcode + */ +parcObject_ImplementNotify(parcFutureTask, PARCFutureTask); + +/** + * Wakes up all threads that are waiting on the given object's lock. + * + * A thread waits on an object by calling one of the wait methods, `parcFutureTask_Wait`, `parcFutureTask_WaitFor`, `parcFutureTask_WaitUntil`. + * The awakened threads will proceed after the current thread relinquishes the lock on the given object. + * The awakened threads will compete in the usual manner with any other threads that might be actively competing + * to synchronize on this object. + * Awakened threads have no priority between them in being the next thread to lock this object. + * + * This method can only be called by a thread that is the owner of this object's lock. + * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * Example: + * @code + * { + * if (parcFutureTask_Lock(object)) { + * parcFutureTask_NotifyAll(object); + * parcFutureTask_Unlock(object); + * } + * } + * @endcode + */ +parcObject_ImplementNotifyAll(parcFutureTask, PARCFutureTask); + +/** + * Causes the calling thread to wait until either another thread invokes the parcFutureTask_Notify() function on the same object. + * * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * Example: + * @code + * { + * + * parcFutureTask_Wait(object); + * } + * @endcode + */ +parcObject_ImplementWait(parcFutureTask, PARCFutureTask); + +/** + * Obtain the lock on the given `PARCFutureTask` instance. + * + * If the lock is already held by another thread, this function will block. + * If the lock is aleady held by the current thread, this function will return `false`. + * + * Implementors must avoid deadlock by attempting to lock the object a second time within the same calling thread. + * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * @return true The lock was obtained successfully. + * @return false The lock is already held by the current thread, or the `PARCFutureTask` is invalid. + * + * Example: + * @code + * { + * if (parcFutureTask_Lock(object)) { + * + * } + * } + * @endcode + */ +parcObject_ImplementLock(parcFutureTask, PARCFutureTask); + +/** + * Try to obtain the advisory lock on the given PARCFutureTask instance. + * + * Once the lock is obtained, the caller must release the lock as soon as possible. + * + * @param [in] object A pointer to a valid PARCFutureTask instance. + * + * @return true The PARCFutureTask is locked. + * @return false The PARCFutureTask is unlocked. + * + * Example: + * @code + * { + * parcFutureTask_TryLock(object); + * } + * @endcode + */ +parcObject_ImplementTryLock(parcFutureTask, PARCFutureTask); + +/** + * Try to unlock the advisory lock on the given `PARCFutureTask` instance. + * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * @return true The `PARCFutureTask` was locked and now is unlocked. + * @return false The `PARCFutureTask` was not locked and remains unlocked. + * + * Example: + * @code + * { + * parcFutureTask_Unlock(object); + * } + * @endcode + */ +parcObject_ImplementUnlock(parcFutureTask, PARCFutureTask); + +/** + * Determine if the advisory lock on the given `PARCFutureTask` instance is locked. + * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * @return true The `PARCFutureTask` is locked. + * @return false The `PARCFutureTask` is unlocked. + * Example: + * @code + * { + * if (parcFutureTask_IsLocked(object)) { + * ... + * } + * } + * @endcode + */ +parcObject_ImplementIsLocked(parcFutureTask, PARCFutureTask); + +/** + * Attempt to cancel the execution of this task. + * + * This will return `false` if the task is already done or has already been cancelled. + * Otherswise, if this task has not started when `parcFutureTask_Cancel` is called, this task will never run. + * + * If the task is already running, the boolean `mayInterruptIfRunning` may cause the task to be interrupted, + * otherwise this function will have no effect. + * + * After this function returns, subsequent calls to `parcFutureTask_IsDone` will always return true. + * Subsequent calls to `parcFutureTask_isCancelled` will always return true if this function returned true. + * + * @param [in] object A pointer to a valid `PARCFutureTask` instance. + * + * @return true The task was cancelled. + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +bool parcFutureTask_Cancel(PARCFutureTask *task, bool mayInterruptIfRunning); + +/** + * Waits if necessary for at most the given time for the computation to complete, and then retrieves its result, if available. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return <#value#> <#explanation#> + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +PARCFutureTaskResult parcFutureTask_Get(const PARCFutureTask *futureTask, const PARCTimeout *timeout); + +/** + * Returns true if this task was cancelled before it completed normally. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return <#value#> <#explanation#> + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +bool parcFutureTask_IsCancelled(const PARCFutureTask *futureTask); + +/** + * Returns true if this task completed. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return <#value#> <#explanation#> + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +bool parcFutureTask_IsDone(const PARCFutureTask *futureTask); + +/** + * Sets this Future to the result of its computation unless it has been cancelled. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return The result returned by the task function. + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +void *parcFutureTask_Run(PARCFutureTask *futureTask); + +/** + * Executes the computation without setting its result, and then resets this future to initial state, failing to do so if the computation encounters an exception or is cancelled. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return true The task was executed. + * @retval false The task was not executed because it was previously completed, or it was cancelled. + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +bool parcFutureTask_RunAndReset(PARCFutureTask *futureTask); + +/** + * Reset the given PARCFutureTask to the intial state, a subsequent ecutes the computation without setting its result, and then resets this future to initial state, failing to do so if the computation encounters an exception or is cancelled. + * + * <#Paragraphs Of Explanation#> + * + * @param [<#in#> | <#out#> | <#in,out#>] <#name#> <#description#> + * + * @return true The task was successfully run + * + * Example: + * @code + * { + * <#example#> + * } + * @endcode + */ +void parcFutureTask_Reset(PARCFutureTask *task); +#endif |