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PhutilSystem.php
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Sun, Nov 24, 22:41

PhutilSystem.php
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<?php
/**
* Interact with the operating system.
*
* @task memory Interacting with System Memory
*/
final class PhutilSystem extends Phobject {
/**
* Get information about total and free memory on the system.
*
* Because "free memory" is a murky concept, the interpretation of the values
* returned from this method will vary from system to system and the numbers
* themselves may be only roughly accurate.
*
* @return map<string, wild> Dictionary of memory information.
* @task memory
*/
public static function getSystemMemoryInformation() {
$meminfo_path = '/proc/meminfo';
if (Filesystem::pathExists($meminfo_path)) {
$meminfo_data = Filesystem::readFile($meminfo_path);
return self::parseMemInfo($meminfo_data);
} else if (Filesystem::binaryExists('vm_stat')) {
list($vm_stat_stdout) = execx('vm_stat');
return self::parseVMStat($vm_stat_stdout);
} else {
throw new Exception(
pht(
'Unable to access %s or `%s` on this system to '.
'get system memory information.',
'/proc/meminfo',
'vm_stat'));
}
}
/**
* Parse the output of `/proc/meminfo`.
*
* See @{method:getSystemMemoryInformation}. This method is used to get memory
* information on Linux.
*
* @param string Raw `/proc/meminfo`.
* @return map<string, wild> Parsed memory information.
* @task memory
*/
public static function parseMemInfo($data) {
$data = phutil_split_lines($data);
$map = array();
foreach ($data as $line) {
list($key, $value) = explode(':', $line, 2);
$key = trim($key);
$value = trim($value);
$matches = null;
if (preg_match('/^(\d+) kB\z/', $value, $matches)) {
$value = (int)$matches[1] * 1024;
}
$map[$key] = $value;
}
$expect = array(
'MemTotal',
'MemFree',
'Buffers',
'Cached',
);
foreach ($expect as $key) {
if (!array_key_exists($key, $map)) {
throw new Exception(
pht(
'Expected to find "%s" in "%s" output, but did not.',
$key,
'/proc/meminfo'));
}
}
$total = $map['MemTotal'];
$free = $map['MemFree'] + $map['Buffers'] + $map['Cached'];
return array(
'total' => $total,
'free' => $free,
);
}
/**
* Parse the output of `vm_stat`.
*
* See @{method:getSystemMemoryInformation}. This method is used to get memory
* information on Mac OS X.
*
* @param string Raw `vm_stat` output.
* @return map<string, wild> Parsed memory information.
* @task memory
*/
public static function parseVMStat($data) {
$data = phutil_split_lines($data);
$page_size = null;
$map = array();
foreach ($data as $line) {
list($key, $value) = explode(':', $line, 2);
$key = trim($key);
$value = trim($value);
$matches = null;
if (preg_match('/page size of (\d+) bytes/', $value, $matches)) {
$page_size = (int)$matches[1];
continue;
}
$value = trim($value, '.');
$map[$key] = $value;
}
if (!$page_size) {
throw new Exception(
pht(
'Expected to find "%s" in `%s` output, but did not.',
'page size',
'vm_stat'));
}
$expect = array(
'Pages free',
'Pages active',
'Pages inactive',
'Pages wired down',
);
foreach ($expect as $key) {
if (!array_key_exists($key, $map)) {
throw new Exception(
pht(
'Expected to find "%s" in `%s` output, but did not.',
$key,
'vm_stat'));
}
}
// NOTE: This calculation probably isn't quite right. In particular,
// the numbers don't exactly add up, and "Pages inactive" includes a
// bunch of disk cache. So these numbers aren't totally reliable and they
// aren't directly comparable to the /proc/meminfo numbers.
$free = $map['Pages free'];
$active = $map['Pages active'];
$inactive = $map['Pages inactive'];
$wired = $map['Pages wired down'];
return array(
'total' => ($free + $active + $inactive + $wired) * $page_size,
'free' => ($free) * $page_size,
);
}
}

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