Current File : /www/varak.net/wiki.varak.net/includes/libs/filebackend/fileop/FileOp.php
<?php
/**
* Helper class for representing operations with transaction support.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup FileBackend
*/
use Psr\Log\LoggerInterface;
/**
* FileBackend helper class for representing operations.
* Do not use this class from places outside FileBackend.
*
* Methods called from FileOpBatch::attempt() should avoid throwing
* exceptions at all costs. FileOp objects should be lightweight in order
* to support large arrays in memory and serialization.
*
* @ingroup FileBackend
* @since 1.19
*/
abstract class FileOp {
/** @var array */
protected $params = [];
/** @var FileBackendStore */
protected $backend;
/** @var LoggerInterface */
protected $logger;
/** @var int */
protected $state = self::STATE_NEW;
/** @var bool */
protected $failed = false;
/** @var bool */
protected $async = false;
/** @var string */
protected $batchId;
/** @var bool Operation is not a no-op */
protected $doOperation = true;
/** @var string */
protected $sourceSha1;
/** @var bool */
protected $overwriteSameCase;
/** @var bool */
protected $destExists;
/* Object life-cycle */
const STATE_NEW = 1;
const STATE_CHECKED = 2;
const STATE_ATTEMPTED = 3;
/**
* Build a new batch file operation transaction
*
* @param FileBackendStore $backend
* @param array $params
* @param LoggerInterface $logger PSR logger instance
* @throws FileBackendError
*/
final public function __construct(
FileBackendStore $backend, array $params, LoggerInterface $logger
) {
$this->backend = $backend;
$this->logger = $logger;
list( $required, $optional, $paths ) = $this->allowedParams();
foreach ( $required as $name ) {
if ( isset( $params[$name] ) ) {
$this->params[$name] = $params[$name];
} else {
throw new InvalidArgumentException( "File operation missing parameter '$name'." );
}
}
foreach ( $optional as $name ) {
if ( isset( $params[$name] ) ) {
$this->params[$name] = $params[$name];
}
}
foreach ( $paths as $name ) {
if ( isset( $this->params[$name] ) ) {
// Normalize paths so the paths to the same file have the same string
$this->params[$name] = self::normalizeIfValidStoragePath( $this->params[$name] );
}
}
}
/**
* Normalize a string if it is a valid storage path
*
* @param string $path
* @return string
*/
protected static function normalizeIfValidStoragePath( $path ) {
if ( FileBackend::isStoragePath( $path ) ) {
$res = FileBackend::normalizeStoragePath( $path );
return $res ?? $path;
}
return $path;
}
/**
* Set the batch UUID this operation belongs to
*
* @param string $batchId
*/
final public function setBatchId( $batchId ) {
$this->batchId = $batchId;
}
/**
* Get the value of the parameter with the given name
*
* @param string $name
* @return mixed Returns null if the parameter is not set
*/
final public function getParam( $name ) {
return $this->params[$name] ?? null;
}
/**
* Check if this operation failed precheck() or attempt()
*
* @return bool
*/
final public function failed() {
return $this->failed;
}
/**
* Get a new empty predicates array for precheck()
*
* @return array
*/
final public static function newPredicates() {
return [ 'exists' => [], 'sha1' => [] ];
}
/**
* Get a new empty dependency tracking array for paths read/written to
*
* @return array
*/
final public static function newDependencies() {
return [ 'read' => [], 'write' => [] ];
}
/**
* Update a dependency tracking array to account for this operation
*
* @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
* @return array
*/
final public function applyDependencies( array $deps ) {
$deps['read'] += array_fill_keys( $this->storagePathsRead(), 1 );
$deps['write'] += array_fill_keys( $this->storagePathsChanged(), 1 );
return $deps;
}
/**
* Check if this operation changes files listed in $paths
*
* @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
* @return bool
*/
final public function dependsOn( array $deps ) {
foreach ( $this->storagePathsChanged() as $path ) {
if ( isset( $deps['read'][$path] ) || isset( $deps['write'][$path] ) ) {
return true; // "output" or "anti" dependency
}
}
foreach ( $this->storagePathsRead() as $path ) {
if ( isset( $deps['write'][$path] ) ) {
return true; // "flow" dependency
}
}
return false;
}
/**
* Get the file journal entries for this file operation
*
* @param array $oPredicates Pre-op info about files (format of FileOp::newPredicates)
* @param array $nPredicates Post-op info about files (format of FileOp::newPredicates)
* @return array
*/
final public function getJournalEntries( array $oPredicates, array $nPredicates ) {
if ( !$this->doOperation ) {
return []; // this is a no-op
}
$nullEntries = [];
$updateEntries = [];
$deleteEntries = [];
$pathsUsed = array_merge( $this->storagePathsRead(), $this->storagePathsChanged() );
foreach ( array_unique( $pathsUsed ) as $path ) {
$nullEntries[] = [ // assertion for recovery
'op' => 'null',
'path' => $path,
'newSha1' => $this->fileSha1( $path, $oPredicates )
];
}
foreach ( $this->storagePathsChanged() as $path ) {
if ( $nPredicates['sha1'][$path] === false ) { // deleted
$deleteEntries[] = [
'op' => 'delete',
'path' => $path,
'newSha1' => ''
];
} else { // created/updated
$updateEntries[] = [
'op' => $this->fileExists( $path, $oPredicates ) ? 'update' : 'create',
'path' => $path,
'newSha1' => $nPredicates['sha1'][$path]
];
}
}
return array_merge( $nullEntries, $updateEntries, $deleteEntries );
}
/**
* Check preconditions of the operation without writing anything.
* This must update $predicates for each path that the op can change
* except when a failing StatusValue object is returned.
*
* @param array &$predicates
* @return StatusValue
*/
final public function precheck( array &$predicates ) {
if ( $this->state !== self::STATE_NEW ) {
return StatusValue::newFatal( 'fileop-fail-state', self::STATE_NEW, $this->state );
}
$this->state = self::STATE_CHECKED;
$status = $this->doPrecheck( $predicates );
if ( !$status->isOK() ) {
$this->failed = true;
}
return $status;
}
/**
* @param array &$predicates
* @return StatusValue
*/
protected function doPrecheck( array &$predicates ) {
return StatusValue::newGood();
}
/**
* Attempt the operation
*
* @return StatusValue
*/
final public function attempt() {
if ( $this->state !== self::STATE_CHECKED ) {
return StatusValue::newFatal( 'fileop-fail-state', self::STATE_CHECKED, $this->state );
} elseif ( $this->failed ) { // failed precheck
return StatusValue::newFatal( 'fileop-fail-attempt-precheck' );
}
$this->state = self::STATE_ATTEMPTED;
if ( $this->doOperation ) {
$status = $this->doAttempt();
if ( !$status->isOK() ) {
$this->failed = true;
$this->logFailure( 'attempt' );
}
} else { // no-op
$status = StatusValue::newGood();
}
return $status;
}
/**
* @return StatusValue
*/
protected function doAttempt() {
return StatusValue::newGood();
}
/**
* Attempt the operation in the background
*
* @return StatusValue
*/
final public function attemptAsync() {
$this->async = true;
$result = $this->attempt();
$this->async = false;
return $result;
}
/**
* Get the file operation parameters
*
* @return array (required params list, optional params list, list of params that are paths)
*/
protected function allowedParams() {
return [ [], [], [] ];
}
/**
* Adjust params to FileBackendStore internal file calls
*
* @param array $params
* @return array (required params list, optional params list)
*/
protected function setFlags( array $params ) {
return [ 'async' => $this->async ] + $params;
}
/**
* Get a list of storage paths read from for this operation
*
* @return array
*/
public function storagePathsRead() {
return [];
}
/**
* Get a list of storage paths written to for this operation
*
* @return array
*/
public function storagePathsChanged() {
return [];
}
/**
* Check for errors with regards to the destination file already existing.
* Also set the destExists, overwriteSameCase and sourceSha1 member variables.
* A bad StatusValue will be returned if there is no chance it can be overwritten.
*
* @param array $predicates
* @return StatusValue
*/
protected function precheckDestExistence( array $predicates ) {
$status = StatusValue::newGood();
// Get hash of source file/string and the destination file
$this->sourceSha1 = $this->getSourceSha1Base36(); // FS file or data string
if ( $this->sourceSha1 === null ) { // file in storage?
$this->sourceSha1 = $this->fileSha1( $this->params['src'], $predicates );
}
$this->overwriteSameCase = false;
$this->destExists = $this->fileExists( $this->params['dst'], $predicates );
if ( $this->destExists ) {
if ( $this->getParam( 'overwrite' ) ) {
return $status; // OK
} elseif ( $this->getParam( 'overwriteSame' ) ) {
$dhash = $this->fileSha1( $this->params['dst'], $predicates );
// Check if hashes are valid and match each other...
if ( !strlen( $this->sourceSha1 ) || !strlen( $dhash ) ) {
$status->fatal( 'backend-fail-hashes' );
} elseif ( $this->sourceSha1 !== $dhash ) {
// Give an error if the files are not identical
$status->fatal( 'backend-fail-notsame', $this->params['dst'] );
} else {
$this->overwriteSameCase = true; // OK
}
return $status; // do nothing; either OK or bad status
} else {
$status->fatal( 'backend-fail-alreadyexists', $this->params['dst'] );
return $status;
}
}
return $status;
}
/**
* precheckDestExistence() helper function to get the source file SHA-1.
* Subclasses should overwride this if the source is not in storage.
*
* @return string|bool Returns false on failure
*/
protected function getSourceSha1Base36() {
return null; // N/A
}
/**
* Check if a file will exist in storage when this operation is attempted
*
* @param string $source Storage path
* @param array $predicates
* @return bool
*/
final protected function fileExists( $source, array $predicates ) {
if ( isset( $predicates['exists'][$source] ) ) {
return $predicates['exists'][$source]; // previous op assures this
} else {
$params = [ 'src' => $source, 'latest' => true ];
return $this->backend->fileExists( $params );
}
}
/**
* Get the SHA-1 of a file in storage when this operation is attempted
*
* @param string $source Storage path
* @param array $predicates
* @return string|bool False on failure
*/
final protected function fileSha1( $source, array $predicates ) {
if ( isset( $predicates['sha1'][$source] ) ) {
return $predicates['sha1'][$source]; // previous op assures this
} elseif ( isset( $predicates['exists'][$source] ) && !$predicates['exists'][$source] ) {
return false; // previous op assures this
} else {
$params = [ 'src' => $source, 'latest' => true ];
return $this->backend->getFileSha1Base36( $params );
}
}
/**
* Get the backend this operation is for
*
* @return FileBackendStore
*/
public function getBackend() {
return $this->backend;
}
/**
* Log a file operation failure and preserve any temp files
*
* @param string $action
*/
final public function logFailure( $action ) {
$params = $this->params;
$params['failedAction'] = $action;
try {
$this->logger->error( static::class .
" failed (batch #{$this->batchId}): " . FormatJson::encode( $params ) );
} catch ( Exception $e ) {
// bad config? debug log error?
}
}
}
Mini Shell