simplify open/close of writeStreams

lib/storage/file.js

@@ -11,6 +11,7 @@ var Meta = require("../metadata");
 var Extras = require("../hk-util");
 
 const readFileBin = require("../stream-file").readFileBin;
+const BatchRead = require("../batch-read");
 
 const Schedule = require("../schedule");
 const isValidChannelId = function (id) {
@@ -59,9 +60,9 @@ var channelExists = function (filepath, cb) {
 };
 
 const destroyStream = function (stream) {
-    stream.close();
+    try { stream.close(); } catch (err) { console.error(err); }
     setTimeout(function () {
-        try { stream.destroy(); } catch (err) { console.log(err); }
+        try { stream.destroy(); } catch (err) { console.error(err); }
     }, 5000);
 };
 
@@ -141,7 +142,6 @@ var closeChannel = function (env, channelName, cb) {
             destroyStream(stream, channelName);
         }
         delete env.channels[channelName];
-        env.openFiles--;
         cb();
     } catch (err) {
         cb(err);
@@ -290,7 +290,7 @@ var writeMetadata = function (env, channelId, data, cb) {
 
 
 // check if a file exists at $path
-var checkPath = function (path, callback) {
+var checkPath = function (path, callback) { // callback's second arg is never used...
     Fs.stat(path, function (err) {
         if (!err) {
             callback(undefined, true);
@@ -632,7 +632,7 @@ var unarchiveChannel = function (env, channelName, cb) {
         }));
     });
 };
-
+/*
 var flushUnusedChannels = function (env, cb, frame) {
     var currentTime = +new Date();
 
@@ -654,6 +654,7 @@ var flushUnusedChannels = function (env, cb, frame) {
     });
     cb();
 };
+*/
 
 /*  channelBytes
     calls back with an error or the size (in bytes) of a channel and its metadata
@@ -686,106 +687,63 @@ var channelBytes = function (env, chanName, cb) {
     });
 };
 
-/*::
-export type ChainPadServer_ChannelInternal_t = {
-    atime: number,
-    writeStream: typeof(process.stdout),
-    whenLoaded: ?Array<(err:?Error, chan:?ChainPadServer_ChannelInternal_t)=>void>,
-    onError: Array<(?Error)=>void>,
-    path: string
-};
-*/
-var getChannel = function ( // XXX BatchRead
-    env,
-    id,
-    _callback /*:(err:?Error, chan:?ChainPadServer_ChannelInternal_t)=>void*/
-) {
-    //console.log("getting channel [%s]", id);
-    var callback = Util.once(Util.mkAsync(_callback));
+var getChannel = function (env, id, _callback) {
+    var cb = Util.once(Util.mkAsync(_callback));
+
+    // if the channel is in memory
     if (env.channels[id]) {
         var chan = env.channels[id];
-        chan.atime = +new Date();
-        if (chan.whenLoaded) {
-            chan.whenLoaded.push(callback);
-        } else {
-            callback(undefined, chan);
-        }
-        return;
+        // delay its pending close a little longer
+        chan.delayClose();
+        // and return its writeStream
+        return void cb(void 0, chan);
     }
 
-    if (env.openFiles >= env.openFileLimit) {
-        // FIXME warn if this is the case?
-        // alternatively use graceful-fs to handle lots of concurrent reads
-        // if you're running out of open files, asynchronously clean up expired files
-        // do it on a shorter timeframe, though (half of normal)
-        setTimeout(function () {
-            //console.log("FLUSHING UNUSED CHANNELS");
-            flushUnusedChannels(env, function () {
-                if (env.verbose) {
-                    console.log("Approaching open file descriptor limit. Cleaning up");
+    // otherwise you need to open it or wait until its pending open completes
+    return void env.batchGetChannel(id, cb, function (done) {
+        var path = mkPath(env, id);
+        var channel = {
+            onError: [],
+        };
+        nThen(function (w) {
+            // create the path to the file if it doesn't exist
+            checkPath(path, w(function (err) {
+                if (err) {
+                    w.abort();
+                    return void done(err);
                 }
-            }, env.channelExpirationMs / 2);
-        });
-    }
-    var path = mkPath(env, id);
-    var channel /*:ChainPadServer_ChannelInternal_t*/ = env.channels[id] = {
-        atime: +new Date(),
-        writeStream: (undefined /*:any*/),
-        whenLoaded: [ callback ],
-        onError: [ ],
-        path: path
-    };
-    var complete = function (err) {
-        var whenLoaded = channel.whenLoaded;
-        // no guarantee stream.on('error') will not cause this to be called multiple times
-        if (!whenLoaded) { return; }
-        channel.whenLoaded = undefined;
-        if (err) {
-            delete env.channels[id];
-        }
-        if (!channel.writeStream) {
-            throw new Error("getChannel() complete called without channel writeStream"); // XXX
-        }
-        whenLoaded.forEach(function (wl) { wl(err, (err) ? undefined : channel); });
-    };
-    var fileExists;
-    nThen(function (waitFor) {
-        checkPath(path, waitFor(function (err, exists) {
-            if (err) {
-                waitFor.abort();
-                return void complete(err);
-            }
-            fileExists = exists;
-        }));
-    }).nThen(function (waitFor) {
-        var stream = channel.writeStream = Fs.createWriteStream(path, { flags: 'a' }); // XXX
-        env.openFiles++;
-        stream.on('open', waitFor());
-        stream.on('error', function (err /*:?Error*/) {
-            env.openFiles--;
-            // this might be called after this nThen block closes.
-            if (channel.whenLoaded) {
-                complete(err);
-            } else {
+            }));
+        }).nThen(function (w) {
+            var stream = channel.writeStream = Fs.createWriteStream(path, { flags: 'a' });
+            stream.on('open', w());
+            stream.on('error', function (err) {
+                w.abort();
+                // this might be called after this nThen block closes.
                 channel.onError.forEach(function (handler) {
                     handler(err);
                 });
-            }
+            });
+        }).nThen(function () {
+            channel.delayClose = Util.throttle(function () {
+                delete env.channels[id];
+                destroyStream(channel.writeStream, path);
+                //console.log("closing writestream");
+            }, 30000);
+            channel.delayClose();
+            env.channels[id] = channel;
+            done(void 0, channel);
         });
-    }).nThen(function () {
-        complete();
     });
 };
 
 // write a message to the disk as raw bytes
 const messageBin = (env, chanName, msgBin, cb) => {
     var complete = Util.once(cb);
-    getChannel(env, chanName, function (err, chan) { // XXX
+    getChannel(env, chanName, function (err, chan) {
         if (!chan) { return void complete(err); }
         chan.onError.push(complete);
         chan.writeStream.write(msgBin, function () {
             chan.onError.splice(chan.onError.indexOf(complete), 1);
-            chan.atime = +new Date(); // XXX we should just throttle closing, much simpler and less error prone
             complete();
         });
     });
@@ -999,8 +957,7 @@ module.exports.create = function (conf, cb) {
         channels: { },
         channelExpirationMs: conf.channelExpirationMs || 30000,
         verbose: conf.verbose,
-        openFiles: 0,
-        openFileLimit: conf.openFileLimit || 2048,
+        batchGetChannel: BatchRead('store_batch_channel'),
     };
     var it;
 
@@ -1232,7 +1189,8 @@ module.exports.create = function (conf, cb) {
             },
             // iterate over open channels and close any that are not active
             flushUnusedChannels: function (cb) {
-                flushUnusedChannels(env, cb);
+                cb("DEPRECATED");
+                //flushUnusedChannels(env, cb);
             },
             // write to a log file
             log: function (channelName, content, cb) {
@@ -1247,7 +1205,8 @@ module.exports.create = function (conf, cb) {
             }
         });
     });
+    /*
     it = setInterval(function () {
         flushUnusedChannels(env, function () { });
-    }, 5000);
+    }, 5000);*/
 };