62 lines
1.6 KiB
JavaScript
62 lines
1.6 KiB
JavaScript
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"use strict";
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module.exports = addCache;
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function addCache(repo, cache) {
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var loadAs = repo.loadAs;
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if (loadAs) repo.loadAs = loadAsCached;
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var saveAs = repo.saveAs;
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if (saveAs) repo.saveAs = saveAsCached;
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var createTree = repo.createTree;
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if (createTree) repo.createTree = createTreeCached;
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function loadAsCached(type, hash, callback) {
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// Next check in disk cache...
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cache.loadAs(type, hash, onCacheLoad);
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function onCacheLoad(err, value) {
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if (err) return callback(err);
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// ...and return if it's there.
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if (value !== undefined) {
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return callback(null, value, hash);
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}
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// Otherwise load from real data source...
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loadAs.call(repo, type, hash, onLoad);
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}
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function onLoad(err, value) {
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if (value === undefined) return callback(err);
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// Store it on disk too...
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// Force the hash to prevent mismatches.
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cache.saveAs(type, value, onSave, hash);
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function onSave(err) {
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if (err) return callback(err);
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// Finally return the value to caller.
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callback(null, value, hash);
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}
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}
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}
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function saveAsCached(type, value, callback) {
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saveAs.call(repo, type, value, onSave);
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function onSave(err, hash) {
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if (err) return callback(err);
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// Store in disk, forcing hash to match.
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cache.saveAs(type, value, callback, hash);
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}
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}
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function createTreeCached(entries, callback) {
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createTree.call(repo, entries, onTree);
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function onTree(err, hash, tree) {
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if (err) return callback(err);
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cache.saveAs("tree", tree, callback, hash);
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}
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}
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}
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