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backend/node_modules/pino/lib/worker.js

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+'use strict'
+
+const EE = require('node:events')
+const { pipeline, PassThrough } = require('node:stream')
+const pino = require('../pino.js')
+const build = require('pino-abstract-transport')
+const loadTransportStreamBuilder = require('./transport-stream')
+
+// This file is not checked by the code coverage tool,
+// as it is not reliable.
+
+/* istanbul ignore file */
+
+/*
+ * > Multiple targets & pipelines
+ *
+ *
+ * ┌─────────────────────────────────────────────────┐    ┌─────┐
+ * │                                                 │    │  p  │
+ * │                                                 │    │  i  │
+ * │                   target                        │    │  n  │
+ * │               │ ────────────────────────────────┼────┤  o  │
+ * │   targets     │   target                        │    │  .  │
+ * │ ────────────► │ ────────────────────────────────┼────┤  m  │       source
+ * │               │   target                        │    │  u  │         │
+ * │               │ ────────────────────────────────┼────┤  l  │         │write
+ * │               │                                 │    │  t  │         ▼
+ * │               │  pipeline   ┌───────────────┐   │    │  i  │      ┌────────┐
+ * │               │ ──────────► │  PassThrough  ├───┼────┤  s  ├──────┤        │
+ * │               │             └───────────────┘   │    │  t  │ write│ Thread │
+ * │               │                                 │    │  r  │◄─────┤ Stream │
+ * │               │  pipeline   ┌───────────────┐   │    │  e  │      │        │
+ * │               │ ──────────► │  PassThrough  ├───┼────┤  a  │      └────────┘
+ * │                             └───────────────┘   │    │  m  │
+ * │                                                 │    │     │
+ * └─────────────────────────────────────────────────┘    └─────┘
+ *
+ *
+ *
+ *  > One single pipeline or target
+ *
+ *
+ *                                                           source
+ *                                                             │
+ * ┌────────────────────────────────────────────────┐          │write
+ * │                                                │          ▼
+ * │                                                │      ┌────────┐
+ * │   targets     │   target                       │      │        │
+ * │ ────────────► │  ──────────────────────────────┤      │        │
+ * │               │                                │      │        │
+ * │                                                ├──────┤        │
+ * │                                                │      │        │
+ * │                                                │      │        │
+ * │                     OR                         │      │        │
+ * │                                                │      │        │
+ * │                                                │      │        │
+ * │                               ┌──────────────┐ │      │        │
+ * │   targets     │   pipeline    │              │ │      │ Thread │
+ * │ ────────────► │  ────────────►│ PassThrough  ├─┤      │ Stream │
+ * │               │               │              │ │      │        │
+ * │                               └──────────────┘ │      │        │
+ * │                                                │      │        │
+ * │                     OR                         │ write│        │
+ * │                                                │◄─────┤        │
+ * │                                                │      │        │
+ * │                ┌──────────────┐                │      │        │
+ * │    pipeline    │              │                │      │        │
+ * │ ──────────────►│ PassThrough  ├────────────────┤      │        │
+ * │                │              │                │      │        │
+ * │                └──────────────┘                │      └────────┘
+ * │                                                │
+ * │                                                │
+ * └────────────────────────────────────────────────┘
+ */
+
+module.exports = async function ({ targets, pipelines, levels, dedupe }) {
+  const targetStreams = []
+
+  // Process targets
+  if (targets && targets.length) {
+    targets = await Promise.all(targets.map(async (t) => {
+      const fn = await loadTransportStreamBuilder(t.target)
+      const stream = await fn(t.options)
+      return {
+        level: t.level,
+        stream
+      }
+    }))
+
+    targetStreams.push(...targets)
+  }
+
+  // Process pipelines
+  if (pipelines && pipelines.length) {
+    pipelines = await Promise.all(
+      pipelines.map(async (p) => {
+        let level
+        const pipeDests = await Promise.all(
+          p.map(async (t) => {
+            // level assigned to pipeline is duplicated over all its targets, just store it
+            level = t.level
+            const fn = await loadTransportStreamBuilder(t.target)
+            const stream = await fn(t.options)
+            return stream
+          }
+          ))
+
+        return {
+          level,
+          stream: createPipeline(pipeDests)
+        }
+      })
+    )
+    targetStreams.push(...pipelines)
+  }
+
+  // Skip building the multistream step if either one single pipeline or target is defined and
+  // return directly the stream instance back to TreadStream.
+  // This is equivalent to define either:
+  //
+  // pino.transport({ target: ... })
+  //
+  // OR
+  //
+  // pino.transport({ pipeline: ... })
+  if (targetStreams.length === 1) {
+    return targetStreams[0].stream
+  } else {
+    return build(process, {
+      parse: 'lines',
+      metadata: true,
+      close (err, cb) {
+        let expected = 0
+        for (const transport of targetStreams) {
+          expected++
+          transport.stream.on('close', closeCb)
+          transport.stream.end()
+        }
+
+        function closeCb () {
+          if (--expected === 0) {
+            cb(err)
+          }
+        }
+      }
+    })
+  }
+
+  // TODO: Why split2 was not used for pipelines?
+  function process (stream) {
+    const multi = pino.multistream(targetStreams, { levels, dedupe })
+    // TODO manage backpressure
+    stream.on('data', function (chunk) {
+      const { lastTime, lastMsg, lastObj, lastLevel } = this
+      multi.lastLevel = lastLevel
+      multi.lastTime = lastTime
+      multi.lastMsg = lastMsg
+      multi.lastObj = lastObj
+
+      // TODO handle backpressure
+      multi.write(chunk + '\n')
+    })
+  }
+
+  /**
+ * Creates a pipeline using the provided streams and return an instance of `PassThrough` stream
+ * as a source for the pipeline.
+ *
+ * @param {(TransformStream|WritableStream)[]} streams An array of streams.
+ *   All intermediate streams in the array *MUST* be `Transform` streams and only the last one `Writable`.
+ * @returns A `PassThrough` stream instance representing the source stream of the pipeline
+ */
+  function createPipeline (streams) {
+    const ee = new EE()
+    const stream = new PassThrough({
+      autoDestroy: true,
+      destroy (_, cb) {
+        ee.on('error', cb)
+        ee.on('closed', cb)
+      }
+    })
+
+    pipeline(stream, ...streams, function (err) {
+      if (err && err.code !== 'ERR_STREAM_PREMATURE_CLOSE') {
+        ee.emit('error', err)
+        return
+      }
+
+      ee.emit('closed')
+    })
+
+    return stream
+  }
+}