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[mediawiki.git] / 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
 */

namespace Wikimedia\FileBackend\FileOps;

use Closure;
use Exception;
use InvalidArgumentException;
use MediaWiki\Json\FormatJson;
use Psr\Log\LoggerInterface;
use StatusValue;
use Wikimedia\FileBackend\FileBackend;
use Wikimedia\FileBackend\FileBackendStore;
use Wikimedia\RequestTimeout\TimeoutException;

/**
 * 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 FileBackendStore */
        protected $backend;
        /** @var LoggerInterface */
        protected $logger;

        /** @var array */
        protected $params = [];

        /** @var int Stage in the operation life-cycle */
        protected $state = self::STATE_NEW;
        /** @var bool Whether the operation pre-check or attempt stage failed */
        protected $failed = false;
        /** @var bool Whether the operation is part of a concurrent sub-batch of operation */
        protected $async = false;
        /** @var bool Whether the operation pre-check stage marked the attempt stage as a no-op */
        protected $noOp = false;

        /** @var bool|null */
        protected $overwriteSameCase;
        /** @var bool|null */
        protected $destExists;

        /** Operation has not yet been pre-checked nor run */
        private const STATE_NEW = 1;
        /** Operation has been pre-checked but not yet attempted */
        private const STATE_CHECKED = 2;
        /** Operation has been attempted */
        private const STATE_ATTEMPTED = 3;

        /**
         * Build a new batch file operation transaction
         *
         * @param FileBackendStore $backend
         * @param array $params
         * @param LoggerInterface $logger PSR logger instance
         */
        final public function __construct(
                FileBackendStore $backend, array $params, LoggerInterface $logger
        ) {
                $this->backend = $backend;
                $this->logger = $logger;
                [ $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;
        }

        /**
         * 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 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::newDependencies()
         * @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::newDependencies()
         * @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;
        }

        /**
         * Do a dry-run precondition check of the operation in the context of op batch
         *
         * Updates the batch predicates for all paths this op can change if an OK status is returned
         *
         * @param FileStatePredicates $predicates Counterfactual file states for the op batch
         * @return StatusValue
         */
        final public function precheck( FileStatePredicates $predicates ) {
                if ( $this->state !== self::STATE_NEW ) {
                        return StatusValue::newFatal( 'fileop-fail-state', self::STATE_NEW, $this->state );
                }
                $this->state = self::STATE_CHECKED;

                $status = StatusValue::newGood();
                foreach ( $this->storagePathsReadOrChanged() as $path ) {
                        if ( !$this->backend->isPathUsableInternal( $path ) ) {
                                $status->fatal( 'backend-fail-usable', $path );
                        }
                }
                if ( !$status->isOK() ) {
                        return $status;
                }

                $opPredicates = $predicates->snapshot( $this->storagePathsReadOrChanged() );
                $status = $this->doPrecheck( $opPredicates, $predicates );
                if ( !$status->isOK() ) {
                        $this->failed = true;
                }

                return $status;
        }

        /**
         * Do a dry-run precondition check of the operation in the context of op batch
         *
         * Updates the batch predicates for all paths this op can change if an OK status is returned
         *
         * @param FileStatePredicates $opPredicates Counterfactual file states for op paths at op start
         * @param FileStatePredicates $batchPredicates Counterfactual file states for the op batch
         * @return StatusValue
         */
        protected function doPrecheck(
                FileStatePredicates $opPredicates,
                FileStatePredicates $batchPredicates
        ) {
                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->noOp ) {
                        $status = StatusValue::newGood(); // no-op
                } else {
                        $status = $this->doAttempt();
                        if ( !$status->isOK() ) {
                                $this->failed = true;
                                $this->logFailure( 'attempt' );
                        }
                }

                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;
        }

        /**
         * Attempt the operation without regards to prechecks
         *
         * @return StatusValue
         */
        final public function attemptQuick() {
                $this->state = self::STATE_CHECKED; // bypassed

                return $this->attempt();
        }

        /**
         * Attempt the operation in the background without regards to prechecks
         *
         * @return StatusValue
         */
        final public function attemptAsyncQuick() {
                $this->state = self::STATE_CHECKED; // bypassed

                return $this->attemptAsync();
        }

        /**
         * 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 [];
        }

        /**
         * Get a list of storage paths read from or written to for this operation
         *
         * @return array
         */
        final public function storagePathsReadOrChanged() {
                return array_values( array_unique(
                        array_merge( $this->storagePathsRead(), $this->storagePathsChanged() )
                ) );
        }

        /**
         * Check for errors with regards to the destination file already existing
         *
         * Also set the destExists and overwriteSameCase member variables.
         * A bad StatusValue will be returned if there is no chance it can be overwritten.
         *
         * @param FileStatePredicates $opPredicates Counterfactual storage path states for this op
         * @param int|false|Closure $sourceSize Source size or idempotent function yielding the size
         * @param string|Closure $sourceSha1 Source hash, or, idempotent function yielding the hash
         * @return StatusValue
         */
        protected function precheckDestExistence(
                FileStatePredicates $opPredicates,
                $sourceSize,
                $sourceSha1
        ) {
                $status = StatusValue::newGood();
                // Record the existence of destination file
                $this->destExists = $this->resolveFileExistence( $this->params['dst'], $opPredicates );
                // Check if an incompatible file exists at the destination
                $this->overwriteSameCase = false;
                if ( $this->destExists ) {
                        if ( $this->getParam( 'overwrite' ) ) {
                                return $status; // OK, no conflict
                        } elseif ( $this->getParam( 'overwriteSame' ) ) {
                                // Operation does nothing other than return an OK or bad status
                                $sourceSize = ( $sourceSize instanceof Closure ) ? $sourceSize() : $sourceSize;
                                $sourceSha1 = ( $sourceSha1 instanceof Closure ) ? $sourceSha1() : $sourceSha1;
                                $dstSha1 = $this->resolveFileSha1Base36( $this->params['dst'], $opPredicates );
                                $dstSize = $this->resolveFileSize( $this->params['dst'], $opPredicates );
                                // Check if hashes are valid and match each other...
                                if ( !strlen( $sourceSha1 ) || !strlen( $dstSha1 ) ) {
                                        $status->fatal( 'backend-fail-hashes' );
                                } elseif ( !is_int( $sourceSize ) || !is_int( $dstSize ) ) {
                                        $status->fatal( 'backend-fail-sizes' );
                                } elseif ( $sourceSha1 !== $dstSha1 || $sourceSize !== $dstSize ) {
                                        // Give an error if the files are not identical
                                        $status->fatal( 'backend-fail-notsame', $this->params['dst'] );
                                } else {
                                        $this->overwriteSameCase = true; // OK
                                }
                        } else {
                                $status->fatal( 'backend-fail-alreadyexists', $this->params['dst'] );
                        }
                } elseif ( $this->destExists === FileBackend::EXISTENCE_ERROR ) {
                        $status->fatal( 'backend-fail-stat', $this->params['dst'] );
                }

                return $status;
        }

        /**
         * Check if a file will exist in storage when this operation is attempted
         *
         * Ideally, the file stat entry should already be preloaded via preloadFileStat().
         * Otherwise, this will query the backend.
         *
         * @param string $source Storage path
         * @param FileStatePredicates $opPredicates Counterfactual storage path states for this op
         * @return bool|null Whether the file will exist or null on error
         */
        final protected function resolveFileExistence( $source, FileStatePredicates $opPredicates ) {
                return $opPredicates->resolveFileExistence(
                        $source,
                        function ( $path ) {
                                return $this->backend->fileExists( [ 'src' => $path, 'latest' => true ] );
                        }
                );
        }

        /**
         * Get the size a file in storage will have when this operation is attempted
         *
         * Ideally, file the stat entry should already be preloaded via preloadFileStat() and
         * the backend tracks hashes as extended attributes. Otherwise, this will query the backend.
         * Get the size of a file in storage when this operation is attempted
         *
         * @param string $source Storage path
         * @param FileStatePredicates $opPredicates Counterfactual storage path states for this op
         * @return int|false False on failure
         */
        final protected function resolveFileSize( $source, FileStatePredicates $opPredicates ) {
                return $opPredicates->resolveFileSize(
                        $source,
                        function ( $path ) {
                                return $this->backend->getFileSize( [ 'src' => $path, 'latest' => true ] );
                        }
                );
        }

        /**
         * Get the SHA-1 of a file in storage when this operation is attempted
         *
         * @param string $source Storage path
         * @param FileStatePredicates $opPredicates Counterfactual storage path states for this op
         * @return string|false The SHA-1 hash the file will have or false if non-existent or on error
         */
        final protected function resolveFileSha1Base36( $source, FileStatePredicates $opPredicates ) {
                return $opPredicates->resolveFileSha1Base36(
                        $source,
                        function ( $path ) {
                                return $this->backend->getFileSha1Base36( [ 'src' => $path, 'latest' => true ] );
                        }
                );
        }

        /**
         * 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: " . FormatJson::encode( $params ) );
                } catch ( TimeoutException $e ) {
                        throw $e;
                } catch ( Exception $e ) {
                        // bad config? debug log error?
                }
        }
}

/** @deprecated class alias since 1.43 */
class_alias( FileOp::class, 'FileOp' );