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SFTP: replace a dropped connection; write the index cache in one transaction

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A Hetzner Storage Box drops an SFTP connection that carried a lot of data
and then stayed quiet for a few minutes; files_external keeps using the dead
client, on which every file looks missing. StorageBackend now checks the
connection after a minute without requests, and replaces a connection that
is dead after a failed request (once per request; put, move and delete are
not repeated). SftpReadStream closes a connection it left in an unknown state.

The verify cache refresh took more than 6 minutes on PostgreSQL for 27,547
packs, one autocommitted insert per pack: putMany()/replaceAll() write in one
transaction. After a verify the cache holds the index files as they are, so a
blob in two packs stays cached for both.
This commit is contained in:
Dillard Blom
2026-10-12 01:58:54 +02:00
parent d659322e60
commit 9c06ab2841
9 changed files with 442 additions and 33 deletions
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lib/Repository/BlobIndex.php
+19 -13
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@@ -28,6 +28,8 @@ final class BlobIndex {
/** @var list<\Closure():void>|null cache writes held back by holdCache(), or null when writing directly */
private ?array $heldCacheWrites = null;
private string $repositoryId = '';
/** Index files written to the cache per database transaction while loading. */
private const CACHE_LOT = 256;
/** @var int index files downloaded by the last load() (for tests and diagnostics) */
public int $downloaded = 0;
@@ -107,11 +109,19 @@ final class BlobIndex {
// the cached packs listed before each one are added first.
$next = 0;
$total = count($fetch);
$toCache = []; // written to the cache a few hundred at a time, each lot in one transaction
foreach ($this->backend->getMany($fetch) as $path => $data) {
$packId = basename($path);
$entries = json_decode($this->cipher->decryptString($data, 'index:' . $packId), true, 512, JSON_THROW_ON_ERROR);
$this->downloaded++;
$this->cache?->put($this->repositoryId, $packId, $entries);
if ($this->cache !== null) {
$toCache[$packId] = $entries;
// a check writes the whole cache afresh at the end
if (!$verify && count($toCache) >= self::CACHE_LOT) {
$this->cache->putMany($this->repositoryId, $toCache);
$toCache = [];
}
}
for (; $next < count($order) && $order[$next] !== $packId; $next++) {
$this->add($order[$next], $cached[$order[$next]] ?? []);
}
@@ -125,20 +135,16 @@ final class BlobIndex {
$this->add($order[$next], $cached[$order[$next]] ?? []);
}
if ($verify && $this->cache !== null) {
// Refresh the cache from what was just verified.
// One pass over the blobs: a pass per pack took half an hour on a 1 TB repository
// (27,547 packs x 400,000 blobs), long enough for the location to drop the idle
// connection before the check went on.
$byPack = [];
foreach ($this->blobs as $id => [$pack, $offset, $length, $raw, $flags]) {
$byPack[$pack][] = ['id' => $id, 'offset' => $offset, 'length' => $length, 'raw' => $raw, 'flags' => $flags];
}
$this->cache->remove($this->repositoryId, array_keys($this->cache->all($this->repositoryId)));
foreach ($byPack as $packId => $entries) {
$this->cache->put($this->repositoryId, $packId, $entries);
}
// Refresh the cache from what was just verified, as the index files list it: a blob in
// two packs is in both rows, so that removing one of the packs leaves the other right.
// In one transaction: one row at a time took more than 6 minutes on a 1 TB repository
// (27,547 packs), long enough for the location to drop the connection.
$this->cache->replaceAll($this->repositoryId, $toCache);
return;
}
if ($toCache !== []) {
$this->cache?->putMany($this->repositoryId, $toCache);
}
$stale = array_keys(array_diff_key($cached, $present));
if ($stale !== []) {
$this->cache?->remove($this->repositoryId, $stale);