bug symfony#18150 [Process] Wait a bit less on Windows (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
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[Process] Wait a bit less on Windows

| Q             | A
| ------------- | ---
| Branch        | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

By using `stream_select` instead of `usleep` when the input is at wait, and by not blocking when the process has halted, we can enhance a bit the performance on Windows.

Commits
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380a54f [Process] Wait a bit less on Windows

Author: nicolas-grekas

src/Symfony/Component/Process/Pipes/UnixPipes.php

@@ -102,7 +102,7 @@ public function readAndWrite($blocking, $close = false)
         unset($r[0]);
 
         // let's have a look if something changed in streams
-        if ($r && false === $n = @stream_select($r, $w, $e, 0, $blocking ? Process::TIMEOUT_PRECISION * 1E6 : 0)) {
+        if (($r || $w) && false === $n = @stream_select($r, $w, $e, 0, $blocking ? Process::TIMEOUT_PRECISION * 1E6 : 0)) {
             // if a system call has been interrupted, forget about it, let's try again
             // otherwise, an error occurred, let's reset pipes
             if (!$this->hasSystemCallBeenInterrupted()) {

src/Symfony/Component/Process/Pipes/WindowsPipes.php

@@ -106,11 +106,15 @@ public function getFiles()
     public function readAndWrite($blocking, $close = false)
     {
         $this->unblock();
-        $this->write();
-
-        $read = array();
-        if ($this->fileHandles && $blocking) {
-            usleep(Process::TIMEOUT_PRECISION * 1E6);
+        $w = $this->write();
+        $read = $r = $e = array();
+
+        if ($blocking) {
+            if ($w) {
+                @stream_select($r, $w, $e, 0, Process::TIMEOUT_PRECISION * 1E6);
+            } elseif ($this->fileHandles) {
+                usleep(Process::TIMEOUT_PRECISION * 1E6);
+            }
         }
         foreach ($this->fileHandles as $type => $fileHandle) {
             $data = stream_get_contents($fileHandle, -1, $this->readBytes[$type]);

src/Symfony/Component/Process/Process.php

@@ -360,8 +360,7 @@ public function wait($callback = null)
         do {
             $this->checkTimeout();
             $running = '\\' === DIRECTORY_SEPARATOR ? $this->isRunning() : $this->processPipes->areOpen();
-            $close = '\\' !== DIRECTORY_SEPARATOR || !$running;
-            $this->readPipes(true, $close);
+            $this->readPipes($running, '\\' !== DIRECTORY_SEPARATOR || !$running);
         } while ($running);
 
         while ($this->isRunning()) {
@@ -1295,14 +1294,15 @@ protected function updateStatus($blocking)
         }
 
         $this->processInformation = proc_get_status($this->process);
+        $running = $this->processInformation['running'];
 
-        $this->readPipes($blocking, '\\' === DIRECTORY_SEPARATOR ? !$this->processInformation['running'] : true);
+        $this->readPipes($running && $blocking, '\\' !== DIRECTORY_SEPARATOR || !$running);
 
         if ($this->fallbackStatus && $this->enhanceSigchildCompatibility && $this->isSigchildEnabled()) {
             $this->processInformation = $this->fallbackStatus + $this->processInformation;
         }
 
-        if (!$this->processInformation['running']) {
+        if (!$running) {
             $this->close();
         }
     }