Parallelize Git operations

lib/async-queue.js

@@ -1,28 +1,72 @@
+class Task {
+  constructor(fn, parallel = true) {
+    this.fn = fn;
+    this.parallel = parallel;
+    this.promise = new Promise((resolve, reject) => {
+      this.resolve = resolve;
+      this.reject = reject;
+    });
+  }
+
+  async execute() {
+    try {
+      const value = await this.fn.call(undefined);
+      this.resolve(value);
+    } catch (err) {
+      this.reject(err);
+    }
+  }
+
+  runsInParallel() {
+    return this.parallel;
+  }
+
+  runsInSerial() {
+    return !this.parallel;
+  }
+
+  getPromise() {
+    return this.promise;
+  }
+}
+
 export default class AsyncQueue {
-  constructor() {
-    this.commandQueue = [];
-    this.running = false;
-  }
-
-  push(fn) {
-    const p = new Promise((resolve, reject) => this.commandQueue.push({fn, resolve, reject}));
-    if (!this.running) { this.processQueue(); }
-    return p;
-  }
-
-  async processQueue() {
-    this.running = true;
-    let lastPromise = Promise.resolve();
-    while (this.commandQueue.length) {
-      const {fn, resolve, reject} = this.commandQueue[0];
-      const run = () => fn();
-      lastPromise = lastPromise.then(run, run);
-      lastPromise.then(resolve, reject);
-      try {
-        await lastPromise; // eslint-disable-line babel/no-await-in-loop
-      } catch (e) { /* nothing */ }
-      this.commandQueue.shift();
+  constructor(options = {}) {
+    this.parallelism = options.parallelism || 1;
+    this.nonParallelizableOperation = false;
+    this.tasksInProgress = 0;
+    this.queue = [];
+  }
+
+  push(fn, {parallel} = {parallel: true}) {
+    const task = new Task(fn, parallel);
+    this.queue.push(task);
+    this.processQueue();
+    return task.getPromise();
+  }
+
+  processQueue() {
+    if (!this.queue.length || this.nonParallelizableOperation) { return; }
+
+    const task = this.queue[0];
+    const canRunParallelOp = task.runsInParallel() && this.tasksInProgress < this.parallelism;
+    const canRunSerialOp = task.runsInSerial() && this.tasksInProgress === 0;
+    if (canRunSerialOp || canRunParallelOp) {
+      this.processTask(task, task.runsInParallel());
+      this.queue.shift();
+      this.processQueue();
     }
-    this.running = false;
+  }
+
+  async processTask(task, runsInParallel) {
+    this.tasksInProgress++;
+    if (!runsInParallel) {
+      this.nonParallelizableOperation = true;
+    }
+
+    await task.execute();
+    this.tasksInProgress--;
+    this.nonParallelizableOperation = false;
+    this.processQueue();
   }
 }

lib/controllers/git-panel-controller.js

@@ -82,18 +82,28 @@ export default class GitPanelController {
 
   @autobind
   async fetchRepositoryData(repository) {
+    const dataPromises = {
+      mergeConflicts: repository.getMergeConflicts(),
+      lastCommit: repository.getLastCommit(),
+      isMerging: repository.isMerging(),
+      branchName: repository.getCurrentBranch(),
+      branches: repository.getBranches(),
+      remoteName: repository.getRemoteForBranch(this.branchName),
+      unstagedChanges: repository.getUnstagedChanges(),
+      stagedChanges: this.fetchStagedChanges(repository),
+    };
     const data = {
-      unstagedChanges: await repository.getUnstagedChanges(),
-      stagedChanges: await this.fetchStagedChanges(repository),
-      mergeConflicts: await repository.getMergeConflicts(),
-      lastCommit: await repository.getLastCommit(),
-      isMerging: await repository.isMerging(),
-      branchName: await repository.getCurrentBranch(),
-      branches: await repository.getBranches(),
+      unstagedChanges: await dataPromises.unstagedChanges,
+      stagedChanges: await dataPromises.stagedChanges,
+      mergeConflicts: await dataPromises.mergeConflicts,
+      lastCommit: await dataPromises.lastCommit,
+      isMerging: await dataPromises.isMerging,
+      branchName: await dataPromises.branchName,
+      branches: await dataPromises.branches,
       mergeMessage: null,
       aheadCount: null,
       behindCount: null,
-      remoteName: await repository.getRemoteForBranch(this.branchName),
+      remoteName: await dataPromises.remoteName,
     };
 
     if (data.remoteName) {

lib/git-shell-out-strategy.js

@@ -1,4 +1,5 @@
 import path from 'path';
+import os from 'os';
 
 import {CompositeDisposable} from 'atom';
 
@@ -30,13 +31,16 @@ function withGpgScript(args) {
 }
 
 export default class GitShellOutStrategy {
-  constructor(workingDir) {
+  static defaultExecArgs = {stdin: null, useGitPromptServer: false, writeOperation: false}
+
+  constructor(workingDir, options = {}) {
     this.workingDir = workingDir;
-    this.commandQueue = new AsyncQueue();
+    const parallelism = options.parallelism || Math.max(3, os.cpus().length);
+    this.commandQueue = new AsyncQueue({parallelism});
   }
 
   // Execute a command and read the output using the embedded Git environment
-  exec(args, stdin = null, useGitPromptServer = false) {
+  exec(args, {stdin, useGitPromptServer, writeOperation} = GitShellOutStrategy.defaultExecArgs) {
     /* eslint-disable no-console */
     const subscriptions = new CompositeDisposable();
 
@@ -86,43 +90,48 @@ export default class GitShellOutStrategy {
       if (process.env.PRINT_GIT_TIMES) {
         console.time(`git:${formattedArgs}`);
       }
-      timingMarker.mark('execute');
-      return GitProcess.exec(args, this.workingDir, options)
-        .then(({stdout, stderr, exitCode}) => {
-          timingMarker.finalize();
-          if (process.env.PRINT_GIT_TIMES) {
-            console.timeEnd(`git:${formattedArgs}`);
-          }
-          if (gitPromptServer) {
-            gitPromptServer.terminate();
-          }
-          subscriptions.dispose();
-          if (exitCode) {
-            const err = new GitError(
-              `${formattedArgs} exited with code ${exitCode}\nstdout: ${stdout}\nstderr: ${stderr}`,
-            );
-            err.code = exitCode;
-            err.stdErr = stderr;
-            err.stdOut = stdout;
-            err.command = formattedArgs;
-            return Promise.reject(err);
-          }
-          return stdout;
+      return new Promise(resolve => {
+        timingMarker.mark('nexttick');
+        setImmediate(() => {
+          timingMarker.mark('execute');
+          resolve(GitProcess.exec(args, this.workingDir, options)
+            .then(({stdout, stderr, exitCode}) => {
+              timingMarker.finalize();
+              if (process.env.PRINT_GIT_TIMES) {
+                console.timeEnd(`git:${formattedArgs}`);
+              }
+              if (gitPromptServer) {
+                gitPromptServer.terminate();
+              }
+              subscriptions.dispose();
+              if (exitCode) {
+                const err = new GitError(
+                  `${formattedArgs} exited with code ${exitCode}\nstdout: ${stdout}\nstderr: ${stderr}`,
+                );
+                err.code = exitCode;
+                err.stdErr = stderr;
+                err.stdOut = stdout;
+                err.command = formattedArgs;
+                return Promise.reject(err);
+              }
+              return stdout;
+            }));
         });
-    });
+      });
+    }, {parallel: !writeOperation});
     /* eslint-enable no-console */
   }
 
   /**
    * Execute a git command that may create a commit. If the command fails because the GPG binary was invoked and unable
    * to acquire a passphrase (because the pinentry program attempted to use a tty), retry with a `GitPromptServer`.
    */
-  gpgExec(args, stdin = null) {
+  gpgExec(args, {stdin} = {stdin: null}) {
     const gpgArgs = withGpgScript(args);
-    return this.exec(gpgArgs, stdin).catch(err => {
+    return this.exec(gpgArgs, {stdin, writeOperation: true}).catch(err => {
       if (err.code === 128 && /gpg failed/.test(err.stdErr)) {
         // Retry with a GitPromptServer
-        return this.exec(gpgArgs, stdin, true);
+        return this.exec(gpgArgs, {stdin, useGitPromptServer: true, writeOperation: true});
       } else {
         throw err;
       }
@@ -144,33 +153,33 @@ export default class GitShellOutStrategy {
   stageFiles(paths) {
     if (paths.length === 0) { return null; }
     const args = ['add'].concat(paths);
-    return this.exec(args);
+    return this.exec(args, {writeOperation: true});
   }
 
   unstageFiles(paths, commit = 'HEAD') {
     if (paths.length === 0) { return null; }
     const args = ['reset', commit, '--'].concat(paths);
-    return this.exec(args);
+    return this.exec(args, {writeOperation: true});
   }
 
   applyPatch(patch, {index} = {}) {
     const args = ['apply', '-'];
     if (index) { args.splice(1, 0, '--cached'); }
-    return this.exec(args, patch);
+    return this.exec(args, {stdin: patch, writeOperation: true});
   }
 
   commit(message, {allowEmpty, amend} = {}) {
     const args = ['commit', '-m', message];
     if (amend) { args.push('--amend'); }
     if (allowEmpty) { args.push('--allow-empty'); }
-    return this.gpgExec(args);
+    return this.gpgExec(args, {writeOperation: true});
   }
 
   /**
    * File Status and Diffs
    */
   async getStatusesForChangedFiles() {
-    const output = await this.exec(['status', '--untracked-files=all', '-z']);
+    const output = await this.exec(['status', '--untracked-files=all', '-z'], {writeOperation: true});
 
     const statusMap = {
       'A': 'added',
@@ -280,7 +289,7 @@ export default class GitShellOutStrategy {
 
   async isPartiallyStaged(filePath) {
     const args = ['status', '--short', '--', filePath];
-    const output = await this.exec(args);
+    const output = await this.exec(args, {writeOperation: true});
     const results = output.trim().split(LINE_ENDING_REGEX);
     if (results.length === 2) {
       return true;
@@ -325,7 +334,7 @@ export default class GitShellOutStrategy {
   }
 
   abortMerge() {
-    return this.exec(['merge', '--abort']);
+    return this.exec(['merge', '--abort'], {writeOperation: true});
   }
 
   /**
@@ -334,7 +343,7 @@ export default class GitShellOutStrategy {
   clone(remoteUrl, options = {}) {
     const args = ['clone', '--no-local', remoteUrl, this.workingDir];
     if (options.bare) { args.push('--bare'); }
-    return this.exec(args);
+    return this.exec(args, {writeOperation: true});
   }
 
   async getRemoteForBranch(branchName) {
@@ -348,20 +357,20 @@ export default class GitShellOutStrategy {
 
   async fetch(branchName) {
     const remote = await this.getRemoteForBranch(branchName);
-    return this.exec(['fetch', remote, branchName], null, true);
+    return this.exec(['fetch', remote, branchName], {useGitPromptServer: true, writeOperation: true});
   }
 
   async pull(branchName) {
     const remote = await this.getRemoteForBranch(branchName);
-    return this.gpgExec(['pull', remote, branchName], null, true);
+    return this.gpgExec(['pull', remote, branchName], {useGitPromptServer: true, writeOperation: true});
   }
 
   async push(branchName, options = {}) {
     const remote = await this.getRemoteForBranch(branchName);
     const args = ['push', remote || 'origin', branchName];
     if (options.setUpstream) { args.push('--set-upstream'); }
     if (options.force) { args.push('--force'); }
-    return this.exec(args, null, true);
+    return this.exec(args, {useGitPromptServer: true, writeOperation: true});
   }
 
   async getAheadCount(branchName) {
@@ -395,15 +404,15 @@ export default class GitShellOutStrategy {
   checkout(branchName, options = {}) {
     const args = ['checkout'];
     if (options.createNew) { args.push('-b'); }
-    return this.exec(args.concat(branchName));
+    return this.exec(args.concat(branchName), {writeOperation: true});
   }
 
   async checkoutFiles(paths, revision) {
     if (paths.length === 0) { return null; }
     try {
       const args = ['checkout'];
       if (revision) { args.push(revision); }
-      return await this.exec(args.concat('--', paths));
+      return await this.exec(args.concat('--', paths), {writeOperation: true});
     } catch (error) {
       const matches = error.stdErr.match(/error: pathspec .* did not match any file\(s\) known to git\./g);
       if (matches.length) {
@@ -449,7 +458,7 @@ export default class GitShellOutStrategy {
     let args = ['config'];
     if (replaceAll) { args.push('--replace-all'); }
     args = args.concat(option, value);
-    return this.exec(args);
+    return this.exec(args, {writeOperation: true});
   }
 
   async getRemotes() {
@@ -472,9 +481,9 @@ export default class GitShellOutStrategy {
   async createBlob({filePath, stdin} = {}) {
     let output;
     if (filePath) {
-      output = await this.exec(['hash-object', '-w', filePath]);
+      output = await this.exec(['hash-object', '-w', filePath], {writeOperation: true});
     } else if (stdin) {
-      output = await this.exec(['hash-object', '-w', '--stdin'], stdin);
+      output = await this.exec(['hash-object', '-w', '--stdin'], {stdin, writeOperation: true});
     } else {
       throw new Error('Must supply file path or stdin');
     }

lib/views/git-timings-view.js

@@ -94,6 +94,7 @@ class MarkerTooltip extends React.Component {
 const COLORS = {
   queued: 'red',
   prepare: 'cyan',
+  nexttick: 'yellow',
   execute: 'green',
 };
 class MarkerSpan extends React.Component {