Remove sleeps from curl handling, select it is responsible for waiting

The current sleeps mean that large files download slowly as select would
return quickly when data has arrived and needs to be processed, but the
sleep waits while the buffers are full.

On the flipside we need to ensure that some code that would keep the CPU
busy if run too often does not get run every time select returns.

src/Composer/Util/Http/CurlDownloader.php

@@ -49,6 +49,7 @@ class CurlDownloader
         CURLM_OUT_OF_MEMORY => array('CURLM_OUT_OF_MEMORY', 'You are doomed.'),
         CURLM_INTERNAL_ERROR => array('CURLM_INTERNAL_ERROR', 'This can only be returned if libcurl bugs. Please report it to us!'),
     );
+    private $lastInfoUpdate = 0;
 
     private static $options = array(
         'http' => array(
@@ -240,6 +241,7 @@ class CurlDownloader
         }
 
         $this->checkCurlResult(curl_multi_add_handle($this->multiHandle, $curlHandle));
+        $this->lastInfoUpdate = 0;
         // TODO progress
 
         return (int) $curlHandle;
@@ -390,6 +392,9 @@ class CurlDownloader
             }
         }
 
+        if (microtime(true) - $this->lastInfoUpdate > 0.1) {
+            $this->lastInfoUpdate = microtime(true);
+
             foreach ($this->jobs as $i => $curlHandle) {
                 if (!isset($this->jobs[$i])) {
                     continue;
@@ -415,6 +420,8 @@ class CurlDownloader
                     // TODO progress
                 }
             }
+
+        }
     }
 
     private function handleRedirect(array $job, Response $response, array $responseInfo)

src/Composer/Util/HttpDownloader.php

@@ -340,8 +340,6 @@ class HttpDownloader
             if (!$this->countActiveJobs($index)) {
                 return;
             }
-
-            usleep(1000);
         }
     }
 

src/Composer/Util/Loop.php

@@ -85,6 +85,7 @@ class Loop
             $progress->start($totalJobs);
         }
 
+        $lastUpdate = 0;
         while (true) {
             $activeJobs = 0;
 
@@ -95,15 +96,20 @@ class Loop
                 $activeJobs += $this->processExecutor->countActiveJobs();
             }
 
-            if ($progress) {
+            if ($progress && microtime(true) - $lastUpdate > 0.1) {
+                $lastUpdate = microtime(true);
+                echo "setting progress\n";
                 $progress->setProgress($progress->getMaxSteps() - $activeJobs);
             }
 
             if (!$activeJobs) {
                 break;
             }
+        }
 
-            usleep(5000);
+        // as we skip progress updates if they are too quick, make sure we do one last one here at 100%
+        if ($progress) {
+            $progress->setProgress($progress->getMaxSteps());
         }
 
         unset($this->currentPromises[$waitIndex]);