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