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Code Issues Releases Wiki Activity

Make "FutureIterator" queue management more formal

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Summary: Depends on D21035. Ref T11968. This allows a "FutureIterator" to hold futures which are blocked because of unresolved dependencies, and makes the resolution process more structured.

Test Plan: Ran unit tests, created this revision.

Maniphest Tasks: T11968

Differential Revision: https://secure.phabricator.com/D21036
This commit is contained in:
epriestley 2020-02-27 06:04:51 -08:00
parent 6b75562c3e
commit cb80f69715
4 changed files with 266 additions and 125 deletions
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64
src/future/Future.php
View file

@ -8,8 +8,11 @@
abstract class Future extends Phobject {
private $hasResult = false;
private $hasStarted = false;
private $hasEnded = false;
private $result;
private $exception;
private $futureKey;
/**
* Is this future's process complete? Specifically, can this future be
@ -36,18 +39,30 @@ abstract class Future extends Phobject {
'timeout.'));
}
if ($this->hasException()) {
throw $this->getException();
}
if (!$this->hasResult()) {
$graph = new FutureIterator(array($this));
$graph->resolveAll();
}
if ($this->hasException()) {
throw $this->getException();
}
return $this->getResult();
}
final public function startFuture() {
if ($this->hasStarted) {
throw new Exception(
pht(
'Future has already started; futures can not start more '.
'than once.'));
}
$this->hasStarted = true;
$this->isReady();
}
final public function updateFuture() {
if ($this->hasException()) {
return;
@ -66,11 +81,28 @@ abstract class Future extends Phobject {
}
}
final public function endFuture() {
if (!$this->hasException() && !$this->hasResult()) {
throw new Exception(
pht(
'Trying to end a future which has no exception and no result. '.
'Futures must resolve before they can be ended.'));
}
if ($this->hasEnded) {
throw new Exception(
pht(
'Future has already ended; futures can not end more '.
'than once.'));
}
$this->hasEnded = true;
}
/**
* Retrieve a list of sockets which we can wait to become readable while
* a future is resolving. If your future has sockets which can be
* `select()`ed, return them here (or in @{method:getWriteSockets}) to make
* the resolve loop do a `select()`. If you do not return sockets in either
* the resolve loop do a `select()`. If you do not return sockets in either
* case, you'll get a busy wait.
*
* @return list A list of sockets which we expect to become readable.
@ -153,5 +185,27 @@ abstract class Future extends Phobject {
return ($this->exception !== null);
}
final public function setFutureKey($key) {
if ($this->futureKey !== null) {
throw new Exception(
pht(
'Future already has a key ("%s") assigned.',
$key));
}
$this->futureKey = $key;
return $this;
}
final public function getFutureKey() {
static $next_key = 1;
if ($this->futureKey === null) {
$this->futureKey = sprintf('Future/%d', $next_key++);
}
return $this->futureKey;
}
}

320
src/future/FutureIterator.php
View file

@ -28,17 +28,22 @@
* @task iterator Iterator Interface
* @task internal Internals
*/
final class FutureIterator extends Phobject implements Iterator {
final class FutureIterator
extends Phobject
implements Iterator {
protected $wait = array();
protected $work = array();
protected $futures = array();
protected $key;
private $hold = array();
private $wait = array();
private $work = array();
protected $limit;
private $futures = array();
private $key;
protected $timeout;
protected $isTimeout = false;
private $limit;
private $timeout;
private $isTimeout = false;
private $hasRewound = false;
/* -( Basics )------------------------------------------------------------- */
@ -52,7 +57,15 @@ final class FutureIterator extends Phobject implements Iterator {
*/
public function __construct(array $futures) {
assert_instances_of($futures, 'Future');
$this->futures = $futures;
$respect_keys = !phutil_is_natural_list($futures);
foreach ($futures as $map_key => $future) {
if ($respect_keys) {
$future->setFutureKey($map_key);
}
$this->addFuture($future);
}
}
@ -63,7 +76,17 @@ final class FutureIterator extends Phobject implements Iterator {
* @task basics
*/
public function resolveAll() {
iterator_to_array($this);
// If a caller breaks out of a "foreach" and then calls "resolveAll()",
// interpret it to mean that we should iterate over whatever futures
// remain.
if ($this->hasRewound) {
while ($this->valid()) {
$this->next();
}
} else {
iterator_to_array($this);
}
}
/**
@ -74,24 +97,20 @@ final class FutureIterator extends Phobject implements Iterator {
* @param Future @{class:Future} to add to iterator
* @task basics
*/
public function addFuture(Future $future, $key = null) {
if ($key === null) {
$this->futures[] = $future;
$this->wait[] = last_key($this->futures);
} else if (!isset($this->futures[$key])) {
$this->futures[$key] = $future;
$this->wait[] = $key;
} else {
throw new Exception(pht('Invalid key %s', $key));
public function addFuture(Future $future) {
$key = $future->getFutureKey();
if (isset($this->futures[$key])) {
throw new Exception(
pht(
'This future graph already has a future with key "%s". Each '.
'future must have a unique key.',
$key));
}
// Start running the future if we don't have $this->limit futures running
// already. updateWorkingSet() won't start running the future if there's no
// limit, so we'll manually poke it here in that case.
$this->updateWorkingSet();
if (!$this->limit) {
$future->isReady();
}
$this->futures[$key] = $future;
$this->hold[$key] = $key;
return $this;
}
@ -150,6 +169,15 @@ final class FutureIterator extends Phobject implements Iterator {
}
public function setMaximumWorkingSetSize($limit) {
$this->limit = $limit;
return $this;
}
public function getMaximumWorkingSetSize() {
return $this->limit;
}
/* -( Iterator Interface )------------------------------------------------- */
@ -157,9 +185,12 @@ final class FutureIterator extends Phobject implements Iterator {
* @task iterator
*/
public function rewind() {
$this->wait = array_keys($this->futures);
$this->work = null;
$this->updateWorkingSet();
if ($this->hasRewound) {
throw new Exception(
pht('Future graphs can not be rewound.'));
}
$this->hasRewound = true;
$this->next();
}
@ -168,95 +199,93 @@ final class FutureIterator extends Phobject implements Iterator {
*/
public function next() {
$this->key = null;
if (!count($this->wait)) {
$this->updateWorkingSet();
if (!$this->work) {
return;
}
$read_sockets = array();
$write_sockets = array();
$start = microtime(true);
$timeout = $this->timeout;
$this->isTimeout = false;
$check = $this->getWorkingSet();
$working_set = array_select_keys($this->futures, $this->work);
$resolve = null;
do {
$read_sockets = array();
$write_sockets = array();
$can_use_sockets = true;
$wait_time = 1;
foreach ($check as $wait => $key) {
$future = $this->futures[$key];
while (true) {
// Update every future first. This is a no-op on futures which have
// already resolved or failed, but we want to give futures an
// opportunity to make progress even if we can resolve something.
foreach ($working_set as $future_key => $future) {
$future->updateFuture();
}
// Check if any future has resolved or failed. If we have any such
// futures, we'll return the first one from the iterator.
$resolve_key = null;
foreach ($working_set as $future_key => $future) {
if ($future->hasException()) {
if ($resolve === null) {
$resolve = $wait;
}
continue;
$resolve_key = $future_key;
break;
}
if ($future->hasResult()) {
if ($resolve === null) {
$resolve = $wait;
}
continue;
$resolve_key = $future_key;
break;
}
}
// We've found a future to resolve, so we're done here for now.
if ($resolve_key !== null) {
$this->moveFutureToDone($resolve_key);
return;
}
// We don't have any futures to resolve yet. Check if we're reached
// an update interval.
$wait_time = 1;
if ($timeout !== null) {
$elapsed = microtime(true) - $start;
if ($elapsed > $timeout) {
$this->isTimeout = true;
return;
}
$got_sockets = false;
$socks = $future->getReadSockets();
if ($socks) {
$got_sockets = true;
foreach ($socks as $socket) {
$read_sockets[] = $socket;
}
$wait_time = min($wait_time, $timeout - $elapsed);
}
// We're going to wait. If possible, we'd like to wait with sockets.
// If we can't, we'll just sleep.
$read_sockets = array();
$write_sockets = array();
foreach ($working_set as $future_key => $future) {
$sockets = $future->getReadSockets();
foreach ($sockets as $socket) {
$read_sockets[] = $socket;
}
$socks = $future->getWriteSockets();
if ($socks) {
$got_sockets = true;
foreach ($socks as $socket) {
$write_sockets[] = $socket;
}
$sockets = $future->getWriteSockets();
foreach ($sockets as $socket) {
$write_sockets[] = $socket;
}
}
// If any currently active future had neither read nor write sockets,
// we can't wait for the current batch of items using sockets.
if (!$got_sockets) {
$can_use_sockets = false;
} else {
$use_sockets = ($read_sockets || $write_sockets);
if ($use_sockets) {
foreach ($working_set as $future) {
$wait_time = min($wait_time, $future->getDefaultWait());
}
$this->waitForSockets($read_sockets, $write_sockets, $wait_time);
} else {
usleep(1000);
}
if ($resolve === null) {
// Check for a setUpdateInterval() timeout.
if ($timeout !== null) {
$elapsed = microtime(true) - $start;
if ($elapsed > $timeout) {
$this->isTimeout = true;
return;
} else {
$wait_time = $timeout - $elapsed;
}
}
if ($can_use_sockets) {
$this->waitForSockets($read_sockets, $write_sockets, $wait_time);
} else {
usleep(1000);
}
}
} while ($resolve === null);
$this->key = $this->wait[$resolve];
unset($this->wait[$resolve]);
$this->updateWorkingSet();
}
}
/**
@ -292,39 +321,96 @@ final class FutureIterator extends Phobject implements Iterator {
/* -( Internals )---------------------------------------------------------- */
/**
* @task internal
*/
protected function getWorkingSet() {
if ($this->work === null) {
return $this->wait;
}
return $this->work;
}
/**
* @task internal
*/
protected function updateWorkingSet() {
if (!$this->limit) {
return;
}
$limit = $this->getMaximumWorkingSetSize();
$work_count = count($this->work);
$old = $this->work;
$this->work = array_slice($this->wait, 0, $this->limit, true);
// If we're already working on the maximum number of futures, we just have
// to wait for something to resolve. There's no benefit to updating the
// queue since we can never make any meaningful progress.
// If we're using a limit, our futures are sleeping and need to be polled
// to begin execution, so poll any futures which weren't in our working set
// before.
foreach ($this->work as $work => $key) {
if (!isset($old[$work])) {
$this->futures[$key]->isReady();
if ($limit) {
if ($work_count >= $limit) {
return;
}
}
// If any futures that are currently held are no longer blocked by
// dependencies, move them from "hold" to "wait".
foreach ($this->hold as $future_key) {
if (!$this->canMoveFutureToWait($future_key)) {
continue;
}
$this->moveFutureToWait($future_key);
}
$wait_count = count($this->wait);
$hold_count = count($this->hold);
if (!$work_count && !$wait_count && $hold_count) {
throw new Exception(
pht(
'Future graph is stalled: some futures are held, but no futures '.
'are waiting or working. The graph can never resolve.'));
}
// Figure out how many futures we can start. If we don't have a limit,
// we can start every waiting future. If we do have a limit, we can only
// start as many futures as we have slots for.
if ($limit) {
$work_limit = min($limit, $wait_count);
} else {
$work_limit = $wait_count;
}
// If we're ready to start futures, start them now.
if ($work_limit) {
foreach ($this->wait as $future_key) {
$this->moveFutureToWork($future_key);
$work_limit--;
if (!$work_limit) {
return;
}
}
}
}
private function canMoveFutureToWait($future_key) {
return true;
}
private function moveFutureToWait($future_key) {
unset($this->hold[$future_key]);
$this->wait[$future_key] = $future_key;
}
private function moveFutureToWork($future_key) {
unset($this->wait[$future_key]);
$this->work[$future_key] = $future_key;
$this->futures[$future_key]->startFuture();
}
private function moveFutureToDone($future_key) {
$this->key = $future_key;
unset($this->work[$future_key]);
// Before we return, do another working set update so we start any
// futures that are ready to go as soon as we can.
$this->updateWorkingSet();
$this->futures[$future_key]->endFuture();
}
/**
* Wait for activity on one of several sockets.

4
src/future/exec/__tests__/ExecFutureTestCase.php
View file

@ -61,7 +61,7 @@ final class ExecFutureTestCase extends PhutilTestCase {
// NOTE: This tests interactions between the resolve() timeout and the
// resolution timeout, which are somewhat similar but not identical.
$future = $this->newSleep(32000)->start();
$future = $this->newSleep(32000);
$future->setTimeout(32000);
// We expect this to return in 0.01s.
@ -77,7 +77,7 @@ final class ExecFutureTestCase extends PhutilTestCase {
// do this, we'll hang when exiting until our subprocess exits (32000
// seconds!)
$future->setTimeout(0.01);
$future->resolve();
$iterator->resolveAll();
}
public function testTerminateWithoutStart() {

3
src/lint/linter/ArcanistFutureLinter.php
View file

@ -15,7 +15,8 @@ abstract class ArcanistFutureLinter extends ArcanistLinter {
$limit = $this->getFuturesLimit();
$this->futures = id(new FutureIterator(array()))->limit($limit);
foreach ($this->buildFutures($paths) as $path => $future) {
$this->futures->addFuture($future, $path);
$future->setFutureKey($path);
$this->futures->addFuture($future);
}
}