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   - [`PoolOptions`](#pooloptions)
  17     - [`ThreadPoolOptions extends PoolOptions`](#threadpooloptions-extends-pooloptions)
  18     - [`ClusterPoolOptions extends PoolOptions`](#clusterpooloptions-extends-pooloptions)
  19 - [Worker](#worker)
  20   - [`class YourWorker extends ThreadWorker/ClusterWorker`](#class-yourworker-extends-threadworkerclusterworker)
  21     - [`YourWorker.hasTaskFunction(name)`](#yourworkerhastaskfunctionname)
  22     - [`YourWorker.addTaskFunction(name, fn)`](#yourworkeraddtaskfunctionname-fn)
  23     - [`YourWorker.removeTaskFunction(name)`](#yourworkerremovetaskfunctionname)
  24     - [`YourWorker.listTaskFunctionNames()`](#yourworkerlisttaskfunctionnames)
  25     - [`YourWorker.setDefaultTaskFunction(name)`](#yourworkersetdefaulttaskfunctionname)
  26
  27 ## Pool
  28
  29 ### `pool = new FixedThreadPool/FixedClusterPool(numberOfThreads/numberOfWorkers, filePath, opts)`
  30
  31 `numberOfThreads/numberOfWorkers` (mandatory) Number of workers for this pool.
  32 `filePath` (mandatory) Path to a file with a worker implementation.
  33 `opts` (optional) An object with the pool options properties described below.
  34
  35 ### `pool = new DynamicThreadPool/DynamicClusterPool(min, max, filePath, opts)`
  36
  37 `min` (mandatory) Same as _FixedThreadPool_/_FixedClusterPool_ numberOfThreads/numberOfWorkers, this number of workers will be always active.
  38 `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).
  39 `filePath` (mandatory) Path to a file with a worker implementation.
  40 `opts` (optional) An object with the pool options properties described below.
  41
  42 ### `pool.execute(data, name, transferList)`
  43
  44 `data` (optional) An object that you want to pass to your worker implementation.
  45 `name` (optional) A string with the task function name that you want to execute on the worker. Default: `'default'`
  46 `transferList` (optional) An array of transferable objects that you want to transfer to your [worker_threads](https://nodejs.org/api/worker_threads.html) worker implementation.
  47
  48 This method is available on both pool implementations and returns a promise with the task function execution response.
  49
  50 ### `pool.start()`
  51
  52 This method is available on both pool implementations and will start the minimum number of workers.
  53
  54 ### `pool.destroy()`
  55
  56 This method is available on both pool implementations and will call the terminate method on each worker.
  57
  58 ### `pool.hasTaskFunction(name)`
  59
  60 `name` (mandatory) The task function name.
  61
  62 This method is available on both pool implementations and returns a boolean.
  63
  64 ### `pool.addTaskFunction(name, fn)`
  65
  66 `name` (mandatory) The task function name.
  67 `fn` (mandatory) The task function.
  68
  69 This method is available on both pool implementations and returns a boolean promise.
  70
  71 ### `pool.removeTaskFunction(name)`
  72
  73 `name` (mandatory) The task function name.
  74
  75 This method is available on both pool implementations and returns a boolean promise.
  76
  77 ### `pool.listTaskFunctionNames()`
  78
  79 This method is available on both pool implementations and returns an array of the task function names.
  80
  81 ### `pool.setDefaultTaskFunction(name)`
  82
  83 `name` (mandatory) The task function name.
  84
  85 This method is available on both pool implementations and returns a boolean promise.
  86
  87 ### `PoolOptions`
  88
  89 An object with these properties:
  90
  91 - `onlineHandler` (optional) - A function that will listen for online event on each worker.
  92   Default: `() => {}`
  93 - `messageHandler` (optional) - A function that will listen for message event on each worker.
  94   Default: `() => {}`
  95 - `errorHandler` (optional) - A function that will listen for error event on each worker.
  96   Default: `() => {}`
  97 - `exitHandler` (optional) - A function that will listen for exit event on each worker.
  98   Default: `() => {}`
  99
 100 - `workerChoiceStrategy` (optional) - The worker choice strategy to use in this pool:
 101
 102   - `WorkerChoiceStrategies.ROUND_ROBIN`: Submit tasks to worker in a round robin fashion
 103   - `WorkerChoiceStrategies.LEAST_USED`: Submit tasks to the worker with the minimum number of executed, executing and queued tasks
 104   - `WorkerChoiceStrategies.LEAST_BUSY`: Submit tasks to the worker with the minimum tasks total execution and wait time
 105   - `WorkerChoiceStrategies.LEAST_ELU`: Submit tasks to the worker with the minimum event loop utilization (ELU)
 106   - `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
 107   - `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)
 108   - `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
 109
 110   `WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN`, `WorkerChoiceStrategies.INTERLEAVED_WEIGHTED_ROUND_ROBIN` and `WorkerChoiceStrategies.FAIR_SHARE` strategies are targeted to heavy and long tasks.
 111   Default: `WorkerChoiceStrategies.ROUND_ROBIN`
 112
 113 - `workerChoiceStrategyOptions` (optional) - The worker choice strategy options object to use in this pool.
 114   Properties:
 115
 116   - `retries` (optional) - The number of retries to perform if no worker is eligible.
 117   - `measurement` (optional) - The measurement to use in worker choice strategies: `runTime`, `waitTime` or `elu`.
 118   - `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.
 119   - `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.
 120   - `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.
 121   - `weights` (optional) - The worker weights to use in weighted round robin worker choice strategies: `{ 0: 200, 1: 300, ..., n: 100 }`.
 122
 123   Default: `{ retries: 6, runTime: { median: false }, waitTime: { median: false }, elu: { median: false } }`
 124
 125 - `startWorkers` (optional) - Start the minimum number of workers at pool initialization.
 126   Default: `true`
 127 - `restartWorkerOnError` (optional) - Restart worker on uncaught error in this pool.
 128   Default: `true`
 129 - `enableEvents` (optional) - Events integrated with async resource emission enablement in this pool.
 130   Default: `true`
 131 - `enableTasksQueue` (optional) - Tasks queue per worker enablement in this pool.
 132   Default: `false`
 133
 134 - `tasksQueueOptions` (optional) - The worker tasks queue options object to use in this pool.
 135   Properties:
 136
 137   - `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.
 138   - `concurrency` (optional) - The maximum number of tasks that can be executed concurrently on a worker. It must be a positive integer.
 139   - `taskStealing` (optional) - Task stealing enablement on empty queue.
 140   - `tasksStealingOnBackPressure` (optional) - Tasks stealing enablement under back pressure.
 141
 142   Default: `{ size: (pool maximum size)^2, concurrency: 1, taskStealing: true, tasksStealingOnBackPressure: true }`
 143
 144 #### `ThreadPoolOptions extends PoolOptions`
 145
 146 - `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.
 147
 148 #### `ClusterPoolOptions extends PoolOptions`
 149
 150 - `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.
 151
 152 - `settings` (optional) - An object with the cluster settings. See [cluster](https://nodejs.org/api/cluster.html#cluster_cluster_settings) for more details.
 153
 154 ## Worker
 155
 156 ### `class YourWorker extends ThreadWorker/ClusterWorker`
 157
 158 `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.
 159 `opts` (optional) An object with these properties:
 160
 161 - `killBehavior` (optional) - Dictates if your worker will be deleted in case a task is active on it.
 162   **KillBehaviors.SOFT**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still executing or queued, then the worker **won't** be deleted.
 163   **KillBehaviors.HARD**: If `currentTime - lastActiveTime` is greater than `maxInactiveTime` but a task is still executing or queued, then the worker will be deleted.
 164   This option only apply to the newly created workers.
 165   Default: `KillBehaviors.SOFT`
 166
 167 - `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.
 168   The last active time of your worker will be updated when it terminates a task.
 169   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.
 170   If `killBehavior` is set to `KillBehaviors.SOFT` your tasks have no timeout and your workers will not be terminated until your task is completed.
 171   Default: `60000`
 172
 173 - `killHandler` (optional) - A function that will be called when a worker is killed.
 174   Default: `() => {}`
 175
 176 #### `YourWorker.hasTaskFunction(name)`
 177
 178 `name` (mandatory) The task function name.
 179
 180 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
 181
 182 #### `YourWorker.addTaskFunction(name, fn)`
 183
 184 `name` (mandatory) The task function name.
 185 `fn` (mandatory) The task function.
 186
 187 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
 188
 189 #### `YourWorker.removeTaskFunction(name)`
 190
 191 `name` (mandatory) The task function name.
 192
 193 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.
 194
 195 #### `YourWorker.listTaskFunctionNames()`
 196
 197 This method is available on both worker implementations and returns an array of the task function names.
 198
 199 #### `YourWorker.setDefaultTaskFunction(name)`
 200
 201 `name` (mandatory) The task function name.
 202
 203 This method is available on both worker implementations and returns `{ status: boolean, error?: Error }`.