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[poolifier.git] / docs / api.md
1 # [API](https://poolifier.github.io/poolifier/)
2
3 ## Table of contents
4
5 - [Pool](#pool)
6 - [`pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`](#pool--new-fixedthreadpoolfixedclusterpoolnumberofthreadsnumberofworkers-filepath-opts)
7 - [`pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`](#pool--new-dynamicthreadpooldynamicclusterpoolmin-max-filepath-opts)
8 - [`pool.execute(data, name, transferList)`](#poolexecutedata-name-transferlist)
9 - [`pool.start()`](#poolstart)
10 - [`pool.destroy()`](#pooldestroy)
11 - [`pool.hasTaskFunction(name)`](#poolhastaskfunctionname)
12 - [`pool.addTaskFunction(name, fn)`](#pooladdtaskfunctionname-fn)
13 - [`pool.removeTaskFunction(name)`](#poolremovetaskfunctionname)
14 - [`pool.listTaskFunctionNames()`](#poollisttaskfunctionnames)
15 - [`pool.setDefaultTaskFunction(name)`](#poolsetdefaulttaskfunctionname)
16 - [Pool options](#pool-options)
17 - [Worker](#worker)
18 - [`class YourWorker extends ThreadWorker/ClusterWorker`](#class-yourworker-extends-threadworkerclusterworker)
19 - [`YourWorker.hasTaskFunction(name)`](#yourworkerhastaskfunctionname)
20 - [`YourWorker.addTaskFunction(name, fn)`](#yourworkeraddtaskfunctionname-fn)
21 - [`YourWorker.removeTaskFunction(name)`](#yourworkerremovetaskfunctionname)
22 - [`YourWorker.listTaskFunctionNames()`](#yourworkerlisttaskfunctionnames)
23 - [`YourWorker.setDefaultTaskFunction(name)`](#yourworkersetdefaulttaskfunctionname)
24
25 ## Pool
26
27 ### `pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`
28
29 `numberOfThreads/numberOfWorkers` (mandatory) Number of workers for this pool.
30 `filePath` (mandatory) Path to a file with a worker implementation.
31 `opts` (optional) An object with the pool options properties described below.
32
33 ### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
34
35 `min` (mandatory) Same as _FixedThreadPool_/_FixedClusterPool_ numberOfThreads/numberOfWorkers, this number of workers will be always active.
36 `max` (mandatory) Max number of workers that this pool can contain, the newly created workers will die after a threshold (default is 1 minute, you can override it in your worker implementation).
37 `filePath` (mandatory) Path to a file with a worker implementation.
38 `opts` (optional) An object with the pool options properties described below.
39
40 ### `pool.execute(data, name, transferList)`
41
42 `data` (optional) An object that you want to pass to your worker task function implementation.
43 `name` (optional) A string with the task function name that you want to execute on the worker. Default: `'default'`
44 `transferList` (optional) An array of transferable objects that you want to transfer to your [`ThreadWorker`](#class-yourworker-extends-threadworkerclusterworker) worker implementation.
45
46 This method is available on both pool implementations and returns a promise with the task function execution response.
47
48 ### `pool.start()`
49
50 This method is available on both pool implementations and will start the minimum number of workers.
51
52 ### `pool.destroy()`
53
54 This method is available on both pool implementations and will call the terminate method on each worker.
55
56 ### `pool.hasTaskFunction(name)`
57
58 `name` (mandatory) The task function name.
59
60 This method is available on both pool implementations and returns a boolean.
61
62 ### `pool.addTaskFunction(name, fn)`
63
64 `name` (mandatory) The task function name.
65 `fn` (mandatory) The task function.
66
67 This method is available on both pool implementations and returns a boolean promise.
68
69 ### `pool.removeTaskFunction(name)`
70
71 `name` (mandatory) The task function name.
72
73 This method is available on both pool implementations and returns a boolean promise.
74
75 ### `pool.listTaskFunctionNames()`
76
77 This method is available on both pool implementations and returns an array of the task function names.
78
79 ### `pool.setDefaultTaskFunction(name)`
80
81 `name` (mandatory) The task function name.
82
83 This method is available on both pool implementations and returns a boolean promise.
84
85 ### Pool options
86
87 An object with these properties:
88
89 - `onlineHandler` (optional) - A function that will listen for online event on each worker.
90 Default: `() => {}`
91 - `messageHandler` (optional) - A function that will listen for message event on each worker.
92 Default: `() => {}`
93 - `errorHandler` (optional) - A function that will listen for error event on each worker.
94 Default: `() => {}`
95 - `exitHandler` (optional) - A function that will listen for exit event on each worker.
96 Default: `() => {}`
97
98 - `workerChoiceStrategy` (optional) - The worker choice strategy to use in this pool:
99
100 - `WorkerChoiceStrategies.ROUND_ROBIN`: Submit tasks to worker in a round robin fashion
101 - `WorkerChoiceStrategies.LEAST_USED`: Submit tasks to the worker with the minimum number of executed, executing and queued tasks
102 - `WorkerChoiceStrategies.LEAST_BUSY`: Submit tasks to the worker with the minimum tasks total execution and wait time
103 - `WorkerChoiceStrategies.LEAST_ELU`: Submit tasks to the worker with the minimum event loop utilization (ELU)
104 - `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN`: Submit tasks to worker by using a [weighted round robin scheduling algorithm](./worker-choice-strategies.md#weighted-round-robin) based on tasks execution time
105 - `WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN`: Submit tasks to worker by using an [interleaved weighted round robin scheduling algorithm](./worker-choice-strategies.md#interleaved-weighted-round-robin-experimental) based on tasks execution time (experimental)
106 - `WorkerChoiceStrategies.FAIR_SHARE`: Submit tasks to worker by using a [fair share scheduling algorithm](./worker-choice-strategies.md#fair-share) based on tasks execution time (the default) or ELU active time
107
108 `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN`, `WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN` and `WorkerChoiceStrategies.FAIR_SHARE` strategies are targeted to heavy and long tasks.
109 Default: `WorkerChoiceStrategies.ROUND_ROBIN`
110
111 - `workerChoiceStrategyOptions` (optional) - The worker choice strategy options object to use in this pool.
112 Properties:
113
114 - `measurement` (optional) - The measurement to use in worker choice strategies: `runTime`, `waitTime` or `elu`.
115 - `runTime` (optional) - Use the tasks [simple moving median](./worker-choice-strategies.md#simple-moving-median) runtime instead of the tasks simple moving average runtime in worker choice strategies.
116 - `waitTime` (optional) - Use the tasks [simple moving median](./worker-choice-strategies.md#simple-moving-median) wait time instead of the tasks simple moving average wait time in worker choice strategies.
117 - `elu` (optional) - Use the tasks [simple moving median](./worker-choice-strategies.md#simple-moving-median) ELU instead of the tasks simple moving average ELU in worker choice strategies.
118 - `weights` (optional) - The worker weights to use in weighted round robin worker choice strategies: `{ 0: 200, 1: 300, ..., n: 100 }`.
119
120 Default: `{ runTime: { median: false }, waitTime: { median: false }, elu: { median: false } }`
121
122 - `startWorkers` (optional) - Start the minimum number of workers at pool initialization.
123 Default: `true`
124 - `restartWorkerOnError` (optional) - Restart worker on uncaught error in this pool.
125 Default: `true`
126 - `enableEvents` (optional) - Events integrated with async resource emission enablement in this pool.
127 Default: `true`
128 - `enableTasksQueue` (optional) - Tasks queue per worker enablement in this pool.
129 Default: `false`
130
131 - `tasksQueueOptions` (optional) - The worker tasks queue options object to use in this pool.
132 Properties:
133
134 - `size` (optional) - The maximum number of tasks that can be queued on a worker before flagging it as back pressured. It must be a positive integer.
135 - `concurrency` (optional) - The maximum number of tasks that can be executed concurrently on a worker. It must be a positive integer.
136 - `taskStealing` (optional) - Task stealing enablement on idle.
137 - `tasksStealingOnBackPressure` (optional) - Tasks stealing enablement under back pressure.
138 - `tasksFinishedTimeout` (optional) - Queued tasks finished timeout in milliseconds at worker termination.
139
140 Default: `{ size: (pool maximum size)^2, concurrency: 1, taskStealing: true, tasksStealingOnBackPressure: true, tasksFinishedTimeout: 2000 }`
141
142 - `workerOptions` (optional) - An object with the worker options to pass to worker. See [worker_threads](https://nodejs.org/api/worker_threads.html#worker_threads_new_worker_filename_options) for more details.
143
144 - `env` (optional) - An object with the environment variables to pass to worker. See [cluster](https://nodejs.org/api/cluster.html#cluster_cluster_fork_env) for more details.
145
146 - `settings` (optional) - An object with the cluster settings. See [cluster](https://nodejs.org/api/cluster.html#cluster_cluster_settings) for more details.
147
148 ## Worker
149
150 ### `class YourWorker extends ThreadWorker/ClusterWorker`
151
152 `taskFunctions` (mandatory) The task function or task functions object `{ name_1: fn_1, ..., name_n: fn_n }` that you want to execute on the worker.
153 `opts` (optional) An object with these properties:
154
155 - `killBehavior` (optional) - Dictates if your worker will be deleted in case a task is active on it.
156 **KillBehaviors.SOFT**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still executing or queued, then the worker **won't** be deleted.
157 **KillBehaviors.HARD**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still executing or queued, then the worker will be deleted.
158 This option only apply to the newly created workers.
159 Default: `KillBehaviors.SOFT`
160
161 - `maxInactiveTime` (optional) - Maximum waiting time in milliseconds for tasks on newly created workers. After this time newly created workers will die. It must be a positive integer greater or equal than 5.
162 The last active time of your worker will be updated when it terminates a task.
163 If `killBehavior` is set to `KillBehaviors.HARD` this value represents also the timeout for the tasks that you submit to the pool, when this timeout expires your tasks is interrupted before completion and removed. The worker is killed if is not part of the minimum size of the pool.
164 If `killBehavior` is set to `KillBehaviors.SOFT` your tasks have no timeout and your workers will not be terminated until your task is completed.
165 Default: `60000`
166
167 - `killHandler` (optional) - A function that will be called when a worker is killed.
168 Default: `() => {}`
169
170 #### `YourWorker.hasTaskFunction(name)`
171
172 `name` (mandatory) The task function name.
173
174 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
175
176 #### `YourWorker.addTaskFunction(name, fn)`
177
178 `name` (mandatory) The task function name.
179 `fn` (mandatory) The task function.
180
181 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
182
183 #### `YourWorker.removeTaskFunction(name)`
184
185 `name` (mandatory) The task function name.
186
187 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
188
189 #### `YourWorker.listTaskFunctionNames()`
190
191 This method is available on both worker implementations and returns an array of the task function names.
192
193 #### `YourWorker.setDefaultTaskFunction(name)`
194
195 `name` (mandatory) The task function name.
196
197 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.