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phab/src/applications/repository/daemon/PhabricatorMercurialGraphStream.php
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PhabricatorMercurialGraphStream.php
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<?php
/**
* Streaming interface on top of "hg log" that gives us performant access to
* the Mercurial commit graph with one nonblocking invocation of "hg". See
* @{class:PhabricatorRepositoryPullLocalDaemon}.
*/
final class PhabricatorMercurialGraphStream {
private $repository;
private $iterator;
private $parents = array();
private $dates = array();
private $local = array();
private $localParents = array();
public function __construct(PhabricatorRepository $repository) {
$this->repository = $repository;
$future = $repository->getLocalCommandFuture(
"log --template '{rev}\1{node}\1{date}\1{parents}\2'");
$this->iterator = new LinesOfALargeExecFuture($future);
$this->iterator->setDelimiter("\2");
$this->iterator->rewind();
}
public function getParents($commit) {
if (!isset($this->parents[$commit])) {
$this->parseUntil('node', $commit);
$local = $this->localParents[$commit];
// The normal parsing pass gives us the local revision numbers of the
// parents, but since we've decided we care about this data, we need to
// convert them into full hashes. To do this, we parse to the deepest
// one and then just look them up.
$parents = array();
if ($local) {
$this->parseUntil('rev', min($local));
foreach ($local as $rev) {
$parents[] = $this->local[$rev];
}
}
$this->parents[$commit] = $parents;
// Throw away the local info for this commit, we no longer need it.
unset($this->localParents[$commit]);
}
return $this->parents[$commit];
}
public function getCommitDate($commit) {
if (!isset($this->dates[$commit])) {
$this->parseUntil('node', $commit);
}
return $this->dates[$commit];
}
/**
* Parse until we have consumed some object. There are two types of parses:
* parse until we find a commit hash ($until_type = "node"), or parse until we
* find a local commit number ($until_type = "rev"). We use the former when
* looking up commits, and the latter when resolving parents.
*/
private function parseUntil($until_type, $until_name) {
if ($this->isParsed($until_type, $until_name)) {
return;
}
$hglog = $this->iterator;
while ($hglog->valid()) {
$line = $hglog->current();
$hglog->next();
$line = trim($line);
if (!strlen($line)) {
break;
}
list($rev, $node, $date, $parents) = explode("\1", $line);
$rev = (int)$rev;
$date = (int)head(explode('.', $date));
$this->dates[$node] = $date;
$this->local[$rev] = $node;
$this->localParents[$node] = $this->parseParents($parents, $rev);
if ($this->isParsed($until_type, $until_name)) {
return;
}
}
throw new Exception(
"No such {$until_type} '{$until_name}' in repository!");
}
/**
* Parse a {parents} template, returning the local commit numbers.
*/
private function parseParents($parents, $target_rev) {
// The hg '{parents}' token is empty if there is one "natural" parent
// (predecessor local commit ID). Othwerwise, it may have one or two
// parents. The string looks like this:
//
// 151:1f6c61a60586 154:1d5f799ebe1e
$parents = trim($parents);
if (strlen($parents)) {
$local = array();
$parents = explode(' ', $parents);
foreach ($parents as $key => $parent) {
$parent = (int)head(explode(':', $parent));
if ($parent == -1) {
// Initial commits will sometimes have "-1" as a parent.
continue;
}
$local[] = $parent;
}
} else if ($target_rev) {
// We have empty parents. If there's a predecessor, that's the local
// parent number.
$local = array($target_rev - 1);
} else {
// Initial commits will sometimes have no parents.
$local = array();
}
return $local;
}
/**
* Returns true if the object specified by $type ('rev' or 'node') and
* $name (rev or node name) has been consumed from the hg process.
*/
private function isParsed($type, $name) {
switch ($type) {
case 'rev':
return isset($this->local[$name]);
case 'node':
return isset($this->dates[$name]);
}
}
}
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