[#182] Support gRPC stream flowable

*  _read method of readable steam learning test
* Max Buffer size
* retry pipe writableStream
* recovery readable stream
* readableStream.closed above node@18
[#177] Update minimum NodeJS version to Node@16

.github/workflows/main.yml

@@ -14,7 +14,6 @@ jobs:
     strategy:
       matrix:
         node_version:
-          - 14          
           - 16
           - 18
 

lib/client/bounded-buffer-readable-stream.js

@@ -0,0 +1,122 @@
+/**
+ * Pinpoint Node.js Agent
+ * Copyright 2021-present NAVER Corp.
+ * Apache License v2.0
+ */
+
+'use strict'
+
+const { Readable } = require('node:stream')
+const log = require('../utils/logger')
+
+class BoundedBufferReadableStream {
+    constructor(constructorOptions) {
+        this.buffer = []
+        this.options = constructorOptions || {}
+        this.readableStream = this.makeReadableSteam()
+        this.maxBufferSize = this.options.maxBuffer || 100
+    }
+
+    makeReadableSteam() {
+        const readableStream = new Readable(Object.assign({
+            read: () => {
+                this.readStart()
+            }
+        }, this.options))
+
+        readableStream.on('error', () => {
+            // https://nodejs.org/api/stream.html#readablepipedestination-options
+            // `One important caveat is that if the Readable stream emits an error during processing, 
+            // the Writable destination is not closed automatically. 
+            // If an error occurs, it will be necessary to manually close each stream 
+            // in order to prevent memory leaks.`
+            // for readable steam error memory leak prevention
+            if (this.writableSteam && typeof this.writableSteam.end === 'function') {
+                this.writableSteam.end()
+            }
+        })
+
+        readableStream.on('close', () => {
+            if (!this.writableFactory) {
+                return
+            }
+
+            this.readableStream = this.makeReadableSteam()
+            this._pipe()
+        })
+
+        return readableStream
+    }
+
+    push(data) {
+        if (this.buffer.length < this.maxBufferSize) {
+            this.buffer.push(data)
+        }
+
+        if (this.canStart()) {
+            this.readStart()
+        }
+    }
+
+    canStart() {
+        return this.readable
+    }
+
+    readStart() {
+        this.readable = true
+
+        const length = this.buffer.length
+        for (let index = 0; index < length; index++) {
+            if (!this.readableStream.push(this.buffer.shift())) {
+                return this.readStop()
+            }
+        }
+    }
+
+    readStop() {
+        this.readable = false
+    }
+
+    end() {
+        this.readableStream.end()
+    }
+
+    pipe(writableFactory) {
+        this.writableFactory = writableFactory
+        this._pipe()
+    }
+
+    _pipe() {
+        if (typeof this.writableFactory !== 'function') {
+            return
+        }
+
+        const writableSteam = this.writableFactory()
+        if (!writableSteam) {
+            return
+        }
+
+        writableSteam.on('error', (error) => {
+            if (error) {
+                log.error('writable steam error', error)
+            }
+        })
+
+        writableSteam.on('unpipe', () => {
+            this.readStop()
+        })
+
+        writableSteam.on('close', () => {
+
+        })
+
+        this.readableStream.pipe(writableSteam)
+        this.writableSteam = writableSteam
+    }
+
+    setEncoding(encoding) {
+        this.readableStream.setEncoding(encoding)
+    }
+}
+
+module.exports = BoundedBufferReadableStream

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pinpoint-node-agent",
-  "version": "0.9.0-next.4",
+  "version": "1.0.0-next.1",
   "main": "index.js",
   "types": "index.d.ts",
   "type": "commonjs",
@@ -23,7 +23,7 @@
   },
   "homepage": "https://github.com/pinpoint-apm/pinpoint-node-agent",
   "engines": {
-    "node": ">=14.0"
+    "node": ">=16.0"
   },
   "keywords": [
     "pinpoint",
@@ -64,7 +64,7 @@
   "devDependencies": {
     "@types/semver": "^7.3.13",
     "@types/shimmer": "^1.0.2",
-    "axios": "^1.6.2",
+    "axios": "^1.6.8",
     "eslint": "^8.43.0",
     "eslint-config-prettier": "^3.6.0",
     "eslint-plugin-import": "^2.25.2",