dillard
ccbbf01c54
A restore read one pack at a time over one SFTP connection, which over a long line is bound by the round trip and by what one TCP connection gets: about 2-3 MiB/s from a Hetzner Storage Box to Canada, with PHP mostly waiting. Repository::restore() now first lists the ranges of packs the restore needs, in order (ReadAheadPlan), and the location reads them ahead into unlinked files in a spool folder in the target (IReadsAhead). Over SFTP, SftpRangeFetcher does that on four connections of its own, 16 requests in flight each, taking the answers of whichever connection has one. A range that fails, a damaged copy, or a blob that moved since the plan is read the usual way, which reports what is wrong. Other locations restore as before. On a test line with 120 ms RTT and 0.2% loss, a 1.6 GiB restore went from 5.1 to 17.8 MiB/s, all files identical.
31 lines
1.3 KiB
PHP
31 lines
1.3 KiB
PHP
<?php
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declare(strict_types=1);
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// SPDX-FileCopyrightText: 2026 Dillard Blom
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// SPDX-License-Identifier: AGPL-3.0-or-later
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namespace OCA\NgBackup\Backend;
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/**
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* A backend that can read many byte ranges ahead of use, several at a time over connections of
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* its own (a full restore, where one connection at a time is bound by the round trip).
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*/
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interface IReadsAhead {
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/** Whether readAhead() is worth planning for: false when it would return null anyway. */
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public function canReadAhead(): bool;
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/**
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* The ranges in the order given, each as a local stream at offset 0 holding its bytes, read a
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* few ranges ahead of the one the caller is at. A stream is closed when the generator is
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* resumed. Null for a range that could not be read this way (a missing object, a server or
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* connection error): the caller reads it the usual way, which reports why.
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*
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* @param list<array{0:string, 1:int, 2:int}> $ranges [path, offset, length] each
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* @param string $spool an existing local directory for the files that hold the ranges
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* @return \Generator<int, resource|null>|null by position in $ranges; null when this backend
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* cannot read ahead now
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*/
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public function readAhead(array $ranges, string $spool): ?\Generator;
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}
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