From 5b38dc0b1097a85b2e4ddb80035ed7e4d1533247 Mon Sep 17 00:00:00 2001
From: jfstephe <john_stephenson_uk@hotmail.com>
Date: Mon, 15 Nov 2021 09:24:19 +0000
Subject: [PATCH] perf(watcher): significantly improved
 addFile/changeFile/removeFile perf

Change to the event handlers so that they don't return the, generally unecessary, list of files which can save around 100ms per-event (depending on machine spec)

BREAKING CHANGE:

Core public API change: Handlers no longer return the list of files, and a separate call is now needed to return that information.
---
 lib/file-list.js            | 13 +++++--------
 test/unit/file-list.spec.js | 28 ++++++++++++++--------------
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/lib/file-list.js b/lib/file-list.js
index 6c9e93d16..16feb1927 100644
--- a/lib/file-list.js
+++ b/lib/file-list.js
@@ -114,6 +114,7 @@ class FileList {
     return lastCompletedRefresh
   }
 
+  // TODO - Change this so that it's not a getter. Getters shouldn't do lots of processing!
   get files () {
     const served = []
     const included = {}
@@ -172,18 +173,18 @@ class FileList {
     const excluded = this._findExcluded(path)
     if (excluded) {
       log.debug(`Add file "${path}" ignored. Excluded by "${excluded}".`)
-      return this.files
+      return
     }
 
     const pattern = this._findIncluded(path)
     if (!pattern) {
       log.debug(`Add file "${path}" ignored. Does not match any pattern.`)
-      return this.files
+      return
     }
 
     if (this._exists(path)) {
       log.debug(`Add file "${path}" ignored. Already in the list.`)
-      return this.files
+      return
     }
 
     const file = new File(path)
@@ -195,7 +196,6 @@ class FileList {
 
     log.info(`Added file "${path}".`)
     this._emitModified()
-    return this.files
   }
 
   async changeFile (path, force) {
@@ -204,7 +204,7 @@ class FileList {
 
     if (!file) {
       log.debug(`Changed file "${path}" ignored. Does not match any file in the list.`)
-      return this.files
+      return
     }
 
     const [stat] = await Promise.all([statAsync(path), this._refreshing])
@@ -214,7 +214,6 @@ class FileList {
       log.info(`Changed file "${path}".`)
       this._emitModified(force)
     }
-    return this.files
   }
 
   async removeFile (path) {
@@ -224,12 +223,10 @@ class FileList {
     if (file) {
       helper.arrayRemove(this._getFilesByPattern(pattern.pattern), file)
       log.info(`Removed file "${path}".`)
-
       this._emitModified()
     } else {
       log.debug(`Removed file "${path}" ignored. Does not match any file in the list.`)
     }
-    return this.files
   }
 }
 
diff --git a/test/unit/file-list.spec.js b/test/unit/file-list.spec.js
index ca2d39fee..89166b5bd 100644
--- a/test/unit/file-list.spec.js
+++ b/test/unit/file-list.spec.js
@@ -464,32 +464,32 @@ describe('FileList', () => {
 
     it('does not add excluded files', () => {
       return list.refresh().then((before) => {
-        return list.addFile('/secret/hello.txt').then((files) => {
-          expect(files.served).to.be.eql(before.served)
+        return list.addFile('/secret/hello.txt').then(() => {
+          expect(list.files.served).to.be.eql(before.served)
         })
       })
     })
 
     it('does not add already existing files', () => {
       return list.refresh().then((before) => {
-        return list.addFile('/some/a.js').then((files) => {
-          expect(files.served).to.be.eql(before.served)
+        return list.addFile('/some/a.js').then(() => {
+          expect(list.files.served).to.be.eql(before.served)
         })
       })
     })
 
     it('does not add unmatching files', () => {
       return list.refresh().then((before) => {
-        return list.addFile('/some/a.ex').then((files) => {
-          expect(files.served).to.be.eql(before.served)
+        return list.addFile('/some/a.ex').then(() => {
+          expect(list.files.served).to.be.eql(before.served)
         })
       })
     })
 
     it('adds the file to the correct bucket', () => {
       return list.refresh().then((before) => {
-        return list.addFile('/some/d.js').then((files) => {
-          expect(pathsFrom(files.served)).to.contain('/some/d.js')
+        return list.addFile('/some/d.js').then(() => {
+          expect(pathsFrom(list.files.served)).to.contain('/some/d.js')
           const bucket = list.buckets.get('/some/*.js')
           expect(pathsFrom(bucket)).to.contain('/some/d.js')
         })
@@ -531,8 +531,8 @@ describe('FileList', () => {
       list = new List(patterns('/a.*'), [], emitter, preprocess)
 
       return list.refresh().then(() => {
-        return list.addFile('/a.js').then((files) => {
-          expect(findFile('/a.js', files.served).mtime).to.eql(new Date('2012-01-01'))
+        return list.addFile('/a.js').then(() => {
+          expect(findFile('/a.js', list.files.served).mtime).to.eql(new Date('2012-01-01'))
         })
       })
     })
@@ -597,10 +597,10 @@ describe('FileList', () => {
         mockFs._touchFile('/some/b.js', '3020-01-01')
         modified.resetHistory()
 
-        return list.changeFile('/some/b.js').then((files) => {
+        return list.changeFile('/some/b.js').then(() => {
           clock.tick(101)
           expect(modified).to.have.been.calledOnce
-          expect(findFile('/some/b.js', files.served).mtime).to.be.eql(new Date('3020-01-01'))
+          expect(findFile('/some/b.js', list.files.served).mtime).to.be.eql(new Date('3020-01-01'))
         })
       })
     })
@@ -719,8 +719,8 @@ describe('FileList', () => {
       return list.refresh().then((files) => {
         modified.resetHistory()
         return list.removeFile('/some/a.js')
-      }).then((files) => {
-        expect(pathsFrom(files.served)).to.be.eql([
+      }).then(() => {
+        expect(pathsFrom(list.files.served)).to.be.eql([
           '/some/b.js',
           '/a.txt'
         ])