more progress on cache, main thing now is to share chains for dirents…

… AFAICT
Markgorden · Jun 13, 2014 · b0afc4a · b0afc4a
1 parent 47f1952
commit b0afc4a
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Showing 4 changed files with 30 additions and 11 deletions.
diff --git a/cache.js b/cache.js
@@ -6,6 +6,7 @@ exports.wrapDriver = function (volume, opts) {
     }, opts);
 
     var cache = {},
+        advice = 'NORMAL',
         secSize = volume.sectorSize;
 
     function _freezeBuffer(b) {
@@ -15,6 +16,7 @@ exports.wrapDriver = function (volume, opts) {
     }
 
     function addToCache(i, data) {
+        if (advice === 'SEQUENTIAL' || advice === 'NOREUSE') return;
         data = _freezeBuffer(data);
         cache[i] = data;
         //if (data.length > secSize) addToCache(i+1, data.slice(secSize));
@@ -32,12 +34,20 @@ exports.wrapDriver = function (volume, opts) {
     return {
         sectorSize: volume.sectorSize,
         numSectors: volume.numSectors,
+        advice: function (val) {
+            if (!arguments) return adviceSource;
+            else advice = val;
+            if (advice === 'SEQUENTIAL' || advice === 'NOREUSE') cache = {};
+            return this;
+        },
         readSectors: function (i, dest, cb) {
             // TODO: handle having partial parts of dest!
             if (i in cache && dest.length === secSize) {
+//console.log("-in cache-", i);
                 cache[i].copy(dest);
                 setImmediate(cb);
             } else volume.readSectors(i, dest, function (e) {
+//console.log("HAD TO READ", i, advice, dest.toString(), Error().stack);
                 if (e) cb(e);
                 else addToCache(i, dest), cb();
             });

diff --git a/chains.js b/chains.js
@@ -4,7 +4,6 @@ var S = require("./structs.js"),
 function _baseChain(vol) {
     var chain = {};
 
-    chain.cacheAdvice = 'NORMAL';
     chain.sectorSize = vol._sectorSize;
 
     function posFromOffset(off) {
@@ -14,10 +13,14 @@ function _baseChain(vol) {
         return {sector:sector, offset:offset};
     }
 
-    var sectorCache = Object.create(null);
-    // TODO: manage sectorCache according to cacheAdvice
-    chain._vol_readSectors = vol._readSectors.bind(vol);
-    chain._vol_writeSectors = vol._writeSectors.bind(vol);
+    var sectorCache = vol._makeCache();
+    Object.defineProperty(chain, 'cacheAdvice', {
+        enumerable: true,
+        get: function () { return sectorCache.advice(); },
+        set: function (v) { sectorCache.advice(v); }
+    });
+    chain._vol_readSectors = vol._readSectors.bind(vol, sectorCache);
+    chain._vol_writeSectors = vol._writeSectors.bind(vol, sectorCache);
 
     chain.readFromPosition = function (targetPos, buffer, cb) {
         if (typeof targetPos === 'number') targetPos = posFromOffset(targetPos);

diff --git a/index.js b/index.js
@@ -74,7 +74,10 @@ exports.createFileSystem = function (volume, opts, cb) {
         fs._releaseEntry = function (entry) {
             if (!entry._k) throw Error("Can't release entry not obtained via _sharedEntryForPath!");
             var d = entriesByPath[entry._k];
-            if (!--d.s) delete entriesByPath[entry._k];
+            d.s -= 1;
+            setTimeout(function () {
+                if (!d.s) delete entriesByPath[entry._k];
+            });
         };
 
         fs._updateEntry = dir.updateEntry.bind(dir, vol);
@@ -117,6 +120,7 @@ exports.createFileSystem = function (volume, opts, cb) {
                 _fd.entry = fileEntry;
                 _fd.chain = fileChain;
                 if (f.append) _fd.pos = _fd.entry._size;
+                if (f._openDir) _fd.chain.cacheAdvice = 'WILLNEED';
                 if (f.truncate && _fd.entry._size) fs.ftruncate(fd, 0, function (e) {
                     cb(e, fd);
                 }, '_nested_');

diff --git a/vol.js b/vol.js
@@ -44,24 +44,26 @@ exports.init = function (volume, opts, bootSector) {
         return firstDataSector + (n-2)*vol._sectorsPerCluster;
     };
 
-    volume = $.wrapDriver(volume);
+    vol._makeCache = function () {
+        return $.wrapDriver(volume);
+    };
 
-    vol._readSectors = function (secNum, dest, cb) {
+    vol._readSectors = function (cache, secNum, dest, cb) {
         if (typeof dest === 'function') {
             cb = dest;
             dest = new Buffer(vol._sectorSize);
         }
         _.log(_.log.DBG, "vol._readSectors", secNum, dest.length);
-        if (secNum < volume.numSectors) volume.readSectors(secNum, dest, function (e) { cb(e, dest); });
+        if (secNum < volume.numSectors) cache.readSectors(secNum, dest, function (e) { cb(e, dest); });
         else throw Error("Invalid sector number!");
     };
 
-    vol._writeSectors = function (secNum, data, cb) {
+    vol._writeSectors = function (cache, secNum, data, cb) {
         _.log(_.log.DBG, "vol._writeSector", secNum, data.length);
         // NOTE: these are internal assertions, public API will get proper `S.err`s
         if (data.length % volume.sectorSize) throw Error("Buffer length not a multiple of sector size");
         else if (opts.ro) throw Error("Read-only filesystem");
-        else if (secNum < volume.numSectors) volume.writeSectors(secNum, data, cb);
+        else if (secNum < volume.numSectors) cache.writeSectors(secNum, data, cb);
         else throw Error("Invalid sector number!");
     };