Remove direct dependency on amphp/file, improve CPU usage and perf

amphp/file was replaced with ResourceInputStream, which might result
in blocking operations, however so far I did not notice any.

Following removal of amphp/file dependency in amphp/dns (at d26f9bb),
this change should (when new version of amphp/dns is released) result in
eliminating requirement of 3 indirect dependencies.

This change improves:
- CPU utilization (from ~51% to ~35%)
- max speed (from 78.8MiB/s to 170MiB/s)

Given stdin `head -c 1G </dev/urandom | pv -q -L 10000000`:

Before:
      83205.359732      task-clock (msec)     #    0.776 CPUs utilized
           279,904      context-switches      #    0.003 M/sec
            15,297      cpu-migrations        #    0.184 K/sec
             5,318      page-faults           #    0.064 K/sec
    79,455,374,201      cycles                #    0.955 GHz
    44,104,516,695      instructions          #    0.56  insn per cycle
     9,306,984,820      branches              #  111.856 M/sec
       452,310,830      branch-misses         #    4.86% of all branches

     107.261390647 seconds time elapsed

After:
      37608.420764      task-clock (msec)     #    0.350 CPUs utilized
            27,243      context-switches      #    0.724 K/sec
             2,032      cpu-migrations        #    0.054 K/sec
             3,261      page-faults           #    0.087 K/sec
    17,073,590,870      cycles                #    0.454 GHz
    12,015,172,856      instructions          #    0.70  insn per cycle
     2,428,621,990      branches              #   64.577 M/sec
        64,394,486      branch-misses         #    2.65% of all branches

     107.449499919 seconds time elapsed

Given `head -c 1G </dev/urandom`:

Before:
      18344.168358      task-clock (msec)     #    1.284 CPUs utilized
           248,097      context-switches      #    0.014 M/sec
             3,901      cpu-migrations        #    0.213 K/sec
             5,285      page-faults           #    0.288 K/sec
    62,863,094,352      cycles                #    3.427 GHz
    42,953,043,093      instructions          #    0.68  insn per cycle
     9,069,974,709      branches              #  494.434 M/sec
       308,754,921      branch-misses         #    3.40% of all branches

      14.290214331 seconds time elapsed

After:
       4913.930543      task-clock (msec)     #    0.737 CPUs utilized
            74,337      context-switches      #    0.015 M/sec
             1,105      cpu-migrations        #    0.225 K/sec
             3,256      page-faults           #    0.663 K/sec
    16,824,387,362      cycles                #    3.424 GHz
    12,426,816,219      instructions          #    0.74  insn per cycle
     2,545,396,441      branches              #  517.996 M/sec
        46,043,534      branch-misses         #    1.81% of all branches

       6.666760699 seconds time elapsed

composer.json

@@ -14,7 +14,6 @@
         "ext-fileinfo": "*",
         "amphp/amp": "^2.0",
         "amphp/byte-stream": "^1.2.5",
-        "amphp/file": "^0.2 || ^0.3",
         "amphp/socket": "^0.10",
         "jean85/pretty-package-versions": "^1.1",
         "psr/log": "^1.0",

src/Responder.php

@@ -2,8 +2,8 @@
 
 namespace Ostrolucky\Stdinho;
 
+use Amp\ByteStream\ResourceInputStream;
 use Amp\ByteStream\StreamException;
-use Amp\File\Handle;
 use Amp\Socket\Socket;
 use Ostrolucky\Stdinho\Bufferer\BuffererInterface;
 use Psr\Log\LoggerInterface;
@@ -27,9 +27,6 @@ public function __invoke(Socket $socket): \Generator
         $remoteAddress = $socket->getRemoteAddress();
         $this->logger->debug("Accepted connection from $remoteAddress:\n" . trim(yield $socket->read()));
 
-        /** @var Handle $handle */
-        $handle = yield \Amp\File\open($this->bufferer->getFilePath(), 'rb');
-
         $header = [
             'HTTP/1.1 200 OK',
             'Content-Type:' . yield $this->bufferer->getMimeType(),
@@ -49,26 +46,42 @@ public function __invoke(Socket $socket): \Generator
             $remoteAddress
         );
 
+        $handle = new ResourceInputStream(fopen($this->bufferer->getFilePath(), 'rb'));
+
         try {
-            while (($chunk = yield $handle->read()) || $this->bufferer->isBuffering()) {
-                // we reached end of the buffer, but it's still buffering
-                if ($chunk === null) {
+            while (true) {
+                $buffererProgress = $this->bufferer->getCurrentProgress();
+
+                /**
+                 * Not trying to read the buffer when connected client caught up to it is important for following:
+                 *
+                 * 1. Reduce CPU usage and potential block operations thanks to avoiding executing logic in read()
+                 * 2. Prevent ResourceInputStream to close the resource when it detects feof. This serves as workaround.
+                 *
+                 * @see https://github.com/ostrolucky/stdinho/pull/2
+                 * @see https://github.com/amphp/byte-stream/issues/47
+                 */
+                if ($buffererProgress <= $progressBar->step && $this->bufferer->isBuffering()) {
                     yield $this->bufferer->waitForWrite();
                     continue;
                 }
 
+                if (($chunk = yield $handle->read()) === null) {
+                    break; // No more buffering and client caught up to it -> finish download
+                }
+
                 yield $socket->write($chunk);
 
                 $progressBar->max = $this->bufferer->getCurrentProgress();
                 $progressBar->advance(strlen($chunk));
-            };
+            }
             $progressBar->finish();
             $this->logger->debug("$remoteAddress finished download");
         } catch (StreamException $exception) {
             $this->logger->debug("$remoteAddress aborted download");
         }
 
-        $handle->end();
+        $handle->close();
         $socket->end();
     }
 }