Provide an API for parsing swap information from "/proc/meminfo"

Summary: Ref T13653. This entirely exists to support converging into the right swap state in deployment workflows.

Test Plan: Ran unit tests.

Maniphest Tasks: T13653

Differential Revision: https://secure.phabricator.com/D21733

src/__phutil_library_map__.php

@@ -264,6 +264,8 @@ phutil_register_library_map(array(
     'ArcanistHgProxyClient' => 'hgdaemon/ArcanistHgProxyClient.php',
     'ArcanistHgProxyServer' => 'hgdaemon/ArcanistHgProxyServer.php',
     'ArcanistHgServerChannel' => 'hgdaemon/ArcanistHgServerChannel.php',
+    'ArcanistHostMemorySnapshot' => 'filesystem/memory/ArcanistHostMemorySnapshot.php',
+    'ArcanistHostMemorySnapshotTestCase' => 'filesystem/memory/__tests__/ArcanistHostMemorySnapshotTestCase.php',
     'ArcanistImplicitConstructorXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistImplicitConstructorXHPASTLinterRule.php',
     'ArcanistImplicitConstructorXHPASTLinterRuleTestCase' => 'lint/linter/xhpast/rules/__tests__/ArcanistImplicitConstructorXHPASTLinterRuleTestCase.php',
     'ArcanistImplicitFallthroughXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistImplicitFallthroughXHPASTLinterRule.php',
@@ -1323,6 +1325,8 @@ phutil_register_library_map(array(
     'ArcanistHgProxyClient' => 'Phobject',
     'ArcanistHgProxyServer' => 'Phobject',
     'ArcanistHgServerChannel' => 'PhutilProtocolChannel',
+    'ArcanistHostMemorySnapshot' => 'Phobject',
+    'ArcanistHostMemorySnapshotTestCase' => 'PhutilTestCase',
     'ArcanistImplicitConstructorXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistImplicitConstructorXHPASTLinterRuleTestCase' => 'ArcanistXHPASTLinterRuleTestCase',
     'ArcanistImplicitFallthroughXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',

src/filesystem/memory/ArcanistHostMemorySnapshot.php

@@ -0,0 +1,156 @@
+<?php
+
+final class ArcanistHostMemorySnapshot
+  extends Phobject {
+
+  private $memorySnapshot;
+
+  public static function newFromRawMeminfo($meminfo_source, $meminfo_raw) {
+    $snapshot = new self();
+
+    $snapshot->memorySnapshot = $snapshot->readMeminfoSnapshot(
+      $meminfo_source,
+      $meminfo_raw);
+
+    return $snapshot;
+  }
+
+  public function getTotalSwapBytes() {
+    $info = $this->getMemorySnapshot();
+    return $info['swap.total'];
+  }
+
+  private function getMemorySnapshot() {
+    if ($this->memorySnapshot === null) {
+      $this->memorySnapshot = $this->newMemorySnapshot();
+    }
+
+    return $this->memorySnapshot;
+  }
+
+  private function newMemorySnapshot() {
+    $meminfo_source = '/proc/meminfo';
+    list($meminfo_raw) = execx('cat %s', $meminfo_source);
+    return $this->readMeminfoSnapshot($meminfo_source, $meminfo_raw);
+  }
+
+  private function readMeminfoSnapshot($meminfo_source, $meminfo_raw) {
+    $meminfo_pattern = '/^([^:]+):\s+(\S+)(?:\s+(kB))?\z/';
+
+    $meminfo_map = array();
+
+    $meminfo_lines = phutil_split_lines($meminfo_raw, false);
+    foreach ($meminfo_lines as $meminfo_line) {
+      $meminfo_parts = phutil_preg_match($meminfo_pattern, $meminfo_line);
+
+      if (!$meminfo_parts) {
+        throw new Exception(
+          pht(
+            'Unable to parse line in meminfo source "%s": "%s".',
+            $meminfo_source,
+            $meminfo_line));
+      }
+
+      $meminfo_key = $meminfo_parts[1];
+      $meminfo_value = $meminfo_parts[2];
+      $meminfo_unit = idx($meminfo_parts, 3);
+
+      if (isset($meminfo_map[$meminfo_key])) {
+        throw new Exception(
+          pht(
+            'Encountered duplicate meminfo key "%s" in meminfo source "%s".',
+            $meminfo_key,
+            $meminfo_source));
+      }
+
+      $meminfo_map[$meminfo_key] = array(
+        'value' => $meminfo_value,
+        'unit' => $meminfo_unit,
+      );
+    }
+
+    $swap_total_bytes = $this->readMeminfoBytes(
+      $meminfo_source,
+      $meminfo_map,
+      'SwapTotal');
+
+    return array(
+      'swap.total' => $swap_total_bytes,
+    );
+  }
+
+  private function readMeminfoBytes(
+    $meminfo_source,
+    $meminfo_map,
+    $meminfo_key) {
+
+    $meminfo_integer = $this->readMeminfoIntegerValue(
+      $meminfo_source,
+      $meminfo_map,
+      $meminfo_key);
+
+    $meminfo_unit = $meminfo_map[$meminfo_key]['unit'];
+    if ($meminfo_unit === null) {
+      throw new Exception(
+        pht(
+          'Expected to find a byte unit for meminfo key "%s" in meminfo '.
+          'source "%s", found no unit.',
+          $meminfo_key,
+          $meminfo_source));
+    }
+
+    if ($meminfo_unit !== 'kB') {
+      throw new Exception(
+        pht(
+          'Expected unit for meminfo key "%s" in meminfo source "%s" '.
+          'to be "kB", found "%s".',
+          $meminfo_key,
+          $meminfo_source,
+          $meminfo_unit));
+    }
+
+    $meminfo_bytes = ($meminfo_integer * 1024);
+
+    return $meminfo_bytes;
+  }
+
+  private function readMeminfoIntegerValue(
+    $meminfo_source,
+    $meminfo_map,
+    $meminfo_key) {
+
+    $meminfo_value = $this->readMeminfoValue(
+      $meminfo_source,
+      $meminfo_map,
+      $meminfo_key);
+
+    if (!phutil_preg_match('/^\d+\z/', $meminfo_value)) {
+      throw new Exception(
+        pht(
+          'Expected to find an integer value for meminfo key "%s" in '.
+          'meminfo source "%s", found "%s".',
+          $meminfo_key,
+          $meminfo_source,
+          $meminfo_value));
+    }
+
+    return (int)$meminfo_value;
+  }
+
+  private function readMeminfoValue(
+    $meminfo_source,
+    $meminfo_map,
+    $meminfo_key) {
+
+    if (!isset($meminfo_map[$meminfo_key])) {
+      throw new Exception(
+        pht(
+          'Expected to find meminfo key "%s" in meminfo source "%s".',
+          $meminfo_key,
+          $meminfo_source));
+    }
+
+    return $meminfo_map[$meminfo_key]['value'];
+  }
+
+}

src/filesystem/memory/__tests__/ArcanistHostMemorySnapshotTestCase.php

@@ -0,0 +1,51 @@
+<?php
+
+final class ArcanistHostMemorySnapshotTestCase
+  extends PhutilTestCase {
+
+  public function testSnapshotSwapTotalBytes() {
+    $test_cases = array(
+      'meminfo_swap_normal.txt' => 4294963200,
+      'meminfo_swap_zero.txt' => 0,
+      'meminfo_swap_missing.txt' => false,
+      'meminfo_swap_invalid.txt' => false,
+      'meminfo_swap_badunits.txt' => false,
+      'meminfo_swap_duplicate.txt' => false,
+    );
+
+    $test_dir = dirname(__FILE__).'/data/';
+
+    foreach ($test_cases as $test_file => $expect) {
+      $test_data = Filesystem::readFile($test_dir.$test_file);
+
+      $caught = null;
+      $actual = null;
+      try {
+        $snapshot = ArcanistHostMemorySnapshot::newFromRawMeminfo(
+          $test_file,
+          $test_data);
+        $actual = $snapshot->getTotalSwapBytes();
+      } catch (Exception $ex) {
+        if ($expect === false) {
+          $caught = $ex;
+        } else {
+          throw $ex;
+        }
+      } catch (Throwable $ex) {
+        throw $ex;
+      }
+
+      if ($expect === false) {
+        $this->assertTrue(
+          ($caught instanceof Exception),
+          pht('Expected exception for "%s".', $test_file));
+      } else {
+        $this->assertEqual(
+          $expect,
+          $actual,
+          pht('Result for "%s".', $test_file));
+      }
+    }
+  }
+
+}

src/filesystem/memory/__tests__/data/meminfo_swap_badunits.txt

@@ -0,0 +1,2 @@
+MemTotal:        8140924 kB
+SwapTotal:       4194 mB

src/filesystem/memory/__tests__/data/meminfo_swap_duplicate.txt

@@ -0,0 +1,3 @@
+MemTotal:        8140924 kB
+SwapTotal:       4194300 kB
+SwapTotal:       4194300 kB

src/filesystem/memory/__tests__/data/meminfo_swap_invalid.txt

@@ -0,0 +1,2 @@
+MemTotal:        8140924 kB
+SwapTotal:       aardvark kB

src/filesystem/memory/__tests__/data/meminfo_swap_missing.txt

@@ -0,0 +1 @@
+MemTotal:        8140924 kB

src/filesystem/memory/__tests__/data/meminfo_swap_normal.txt

@@ -0,0 +1,51 @@
+MemTotal:        8140924 kB
+MemFree:         1760456 kB
+MemAvailable:    4264888 kB
+Buffers:           36784 kB
+Cached:          2654788 kB
+SwapCached:         2132 kB
+Active:           331128 kB
+Inactive:        5677400 kB
+Active(anon):      22692 kB
+Inactive(anon):  3325560 kB
+Active(file):     308436 kB
+Inactive(file):  2351840 kB
+Unevictable:       23012 kB
+Mlocked:           18476 kB
+SwapTotal:       4194300 kB
+SwapFree:        2440444 kB
+Dirty:                44 kB
+Writeback:             0 kB
+AnonPages:       3337944 kB
+Mapped:           117424 kB
+Shmem:             19872 kB
+KReclaimable:     124728 kB
+Slab:             240640 kB
+SReclaimable:     124728 kB
+SUnreclaim:       115912 kB
+KernelStack:        6736 kB
+PageTables:        42044 kB
+NFS_Unstable:          0 kB
+Bounce:                0 kB
+WritebackTmp:          0 kB
+CommitLimit:     8264760 kB
+Committed_AS:    6994880 kB
+VmallocTotal:   34359738367 kB
+VmallocUsed:       16656 kB
+VmallocChunk:          0 kB
+Percpu:             9856 kB
+HardwareCorrupted:     0 kB
+AnonHugePages:         0 kB
+ShmemHugePages:        0 kB
+ShmemPmdMapped:        0 kB
+FileHugePages:         0 kB
+FilePmdMapped:         0 kB
+HugePages_Total:       0
+HugePages_Free:        0
+HugePages_Rsvd:        0
+HugePages_Surp:        0
+Hugepagesize:       2048 kB
+Hugetlb:               0 kB
+DirectMap4k:      270336 kB
+DirectMap2M:     8118272 kB
+DirectMap1G:     1048576 kB

src/filesystem/memory/__tests__/data/meminfo_swap_zero.txt

@@ -0,0 +1,51 @@
+MemTotal:        8140924 kB
+MemFree:         1760456 kB
+MemAvailable:    4264888 kB
+Buffers:           36784 kB
+Cached:          2654788 kB
+SwapCached:         2132 kB
+Active:           331128 kB
+Inactive:        5677400 kB
+Active(anon):      22692 kB
+Inactive(anon):  3325560 kB
+Active(file):     308436 kB
+Inactive(file):  2351840 kB
+Unevictable:       23012 kB
+Mlocked:           18476 kB
+SwapTotal:       0 kB
+SwapFree:        2440444 kB
+Dirty:                44 kB
+Writeback:             0 kB
+AnonPages:       3337944 kB
+Mapped:           117424 kB
+Shmem:             19872 kB
+KReclaimable:     124728 kB
+Slab:             240640 kB
+SReclaimable:     124728 kB
+SUnreclaim:       115912 kB
+KernelStack:        6736 kB
+PageTables:        42044 kB
+NFS_Unstable:          0 kB
+Bounce:                0 kB
+WritebackTmp:          0 kB
+CommitLimit:     8264760 kB
+Committed_AS:    6994880 kB
+VmallocTotal:   34359738367 kB
+VmallocUsed:       16656 kB
+VmallocChunk:          0 kB
+Percpu:             9856 kB
+HardwareCorrupted:     0 kB
+AnonHugePages:         0 kB
+ShmemHugePages:        0 kB
+ShmemPmdMapped:        0 kB
+FileHugePages:         0 kB
+FilePmdMapped:         0 kB
+HugePages_Total:       0
+HugePages_Free:        0
+HugePages_Rsvd:        0
+HugePages_Surp:        0
+Hugepagesize:       2048 kB
+Hugetlb:               0 kB
+DirectMap4k:      270336 kB
+DirectMap2M:     8118272 kB
+DirectMap1G:     1048576 kB