finally untangle metadata and index caches

lib/commands/metadata.js

@@ -139,16 +139,10 @@ Data.setMetadata = function (Env, safeKey, data, cb, Server) {
                 next();
 
                 const metadata_cache = Env.metadata_cache;
-                const channel_cache = Env.channel_cache;
 
                 // update the cached metadata
                 metadata_cache[channel] = metadata;
 
-                // as well as the metadata that's attached to the index...
-                // XXX determine if we actually need this...
-                var index = Util.find(channel_cache, [channel, 'index']);
-                if (index && typeof(index) === 'object') { index.metadata = metadata; }
-
                 // it's easy to check if the channel is restricted
                 const isRestricted = metadata.restricted;
                 // and these values will be used in any case

lib/hk-util.js

@@ -227,7 +227,6 @@ const computeIndex = function (Env, channelName, cb) {
 
     const cpIndex = [];
     let messageBuf = [];
-    let metadata;
     let i = 0;
 
     const CB = Util.once(cb);
@@ -235,14 +234,9 @@ const computeIndex = function (Env, channelName, cb) {
     const offsetByHash = {};
     let size = 0;
     nThen(function (w) {
-        getMetadata(Env, channelName, w(function (err, _metadata) {
-            //if (err) { console.log(err); }
-            metadata = _metadata;
-        }));
-    }).nThen(function (w) {
         // iterate over all messages in the channel log
         // old channels can contain metadata as the first message of the log
-        // remember metadata the first time you encounter it
+        // skip over metadata as that is handled elsewhere
         // otherwise index important messages in the log
         store.readMessagesBin(channelName, 0, (msgObj, readMore) => {
             let msg;
@@ -303,7 +297,7 @@ const computeIndex = function (Env, channelName, cb) {
             cpIndex: sliceCpIndex(cpIndex, i),
             offsetByHash: offsetByHash,
             size: size,
-            metadata: metadata,
+            //metadata: metadata,
             line: i
         });
     });
@@ -613,11 +607,40 @@ const handleRPC = function (Env, Server, seq, userId, parsed) {
     }
 };
 
+/*
+    This is called when a user tries to connect to a channel that doesn't exist.
+    we initialize that channel by writing the metadata supplied by the user to its log.
+    if the provided metadata has an expire time then we also create a task to expire it.
+*/
+const handleFirstMessage = function (Env, channelName, metadata) {
+    Env.store.writeMetadata(channelName, JSON.stringify(metadata), function (err) {
+        if (err) {
+            // FIXME tell the user that there was a channel error?
+            return void Env.Log.error('HK_WRITE_METADATA', {
+                channel: channelName,
+                error: err,
+            });
+        }
+    });
+
+    // write tasks
+    if(metadata.expire && typeof(metadata.expire) === 'number') {
+        // the fun part...
+        // the user has said they want this pad to expire at some point
+        Env.tasks.write(metadata.expire, "EXPIRE", [ channelName ], function (err) {
+            if (err) {
+                // if there is an error, we don't want to crash the whole server...
+                // just log it, and if there's a problem you'll be able to fix it
+                // at a later date with the provided information
+                Env.Log.error('HK_CREATE_EXPIRE_TASK', err);
+                Env.Log.info('HK_INVALID_EXPIRE_TASK', JSON.stringify([metadata.expire, 'EXPIRE', channelName]));
+            }
+        });
+    }
+};
+
 const handleGetHistory = function (Env, Server, seq, userId, parsed) {
-    const store = Env.store;
-    const tasks = Env.tasks;
     const metadata_cache = Env.metadata_cache;
-    const channel_cache = Env.channel_cache;
     const HISTORY_KEEPER_ID = Env.id;
     const Log = Env.Log;
 
@@ -656,30 +679,33 @@ const handleGetHistory = function (Env, Server, seq, userId, parsed) {
 
     nThen(function (waitFor) {
         var w = waitFor();
-
+        /*  fetch the channel's metadata.
-        /*  unless this is a young channel, we will serve all messages from an offset
+            use it to check if the channel has expired.
-            this will not include the channel metadata, so we need to explicitly fetch that.
+            send it to the client if it exists.
-            unfortunately, we can't just serve it blindly, since then young channels will
-            send the metadata twice, so let's do a quick check of what we're going to serve...
         */
-        getIndex(Env, channelName, waitFor((err, index) => {
+        getMetadata(Env, channelName, waitFor(function (err, metadata) {
-            /*  if there's an error here, it should be encountered
+            if (err) {
-                and handled by the next nThen block.
+                Env.Log.error('HK_GET_HISTORY_METADATA', {
-                so, let's just fall through...
+                    channel: channelName,
-            */
+                    error: err,
-            if (err) { return w(); }
+                });
-
+                return void w();
+            }
+            if (!metadata || !metadata.channel) { return w(); }
+            // if there is already a metadata log then use it instead
+            // of whatever the user supplied
 
             // it's possible that the channel doesn't have metadata
             // but in that case there's no point in checking if the channel expired
             // or in trying to send metadata, so just skip this block
-            if (!index || !index.metadata) { return void w(); }
+            if (!metadata) { return void w(); }
+
             // And then check if the channel is expired. If it is, send the error and abort
             // FIXME this is hard to read because 'checkExpired' has side effects
             if (checkExpired(Env, Server, channelName)) { return void waitFor.abort(); }
 
             // always send metadata with GET_HISTORY requests
-            Server.send(userId, [0, HISTORY_KEEPER_ID, 'MSG', userId, JSON.stringify(index.metadata)], w);
+            Server.send(userId, [0, HISTORY_KEEPER_ID, 'MSG', userId, JSON.stringify(metadata)], w);
         }));
     }).nThen(() => {
         let msgCount = 0;
@@ -699,45 +725,8 @@ const handleGetHistory = function (Env, Server, seq, userId, parsed) {
                 return;
             }
 
-            const chan = channel_cache[channelName];
-
             if (msgCount === 0 && !metadata_cache[channelName] && Server.channelContainsUser(channelName, userId)) {
-                metadata_cache[channelName] = metadata;
+                handleFirstMessage(Env, channelName, metadata);
-
-                // the index will have already been constructed and cached at this point
-                // but it will not have detected any metadata because it hasn't been written yet
-                // this means that the cache starts off as invalid, so we have to correct it
-                if (chan && chan.index) { chan.index.metadata = metadata; }
-
-                // new channels will always have their metadata written to a dedicated metadata log
-                // but any lines after the first which are not amendments in a particular format will be ignored.
-                // Thus we should be safe from race conditions here if just write metadata to the log as below...
-                // TODO validate this logic
-                // otherwise maybe we need to check that the metadata log is empty as well
-                store.writeMetadata(channelName, JSON.stringify(metadata), function (err) {
-                    if (err) {
-                        // FIXME tell the user that there was a channel error?
-                        return void Log.error('HK_WRITE_METADATA', {
-                            channel: channelName,
-                            error: err,
-                        });
-                    }
-                });
-
-                // write tasks
-                if(metadata.expire && typeof(metadata.expire) === 'number') {
-                    // the fun part...
-                    // the user has said they want this pad to expire at some point
-                    tasks.write(metadata.expire, "EXPIRE", [ channelName ], function (err) {
-                        if (err) {
-                            // if there is an error, we don't want to crash the whole server...
-                            // just log it, and if there's a problem you'll be able to fix it
-                            // at a later date with the provided information
-                            Log.error('HK_CREATE_EXPIRE_TASK', err);
-                            Log.info('HK_INVALID_EXPIRE_TASK', JSON.stringify([metadata.expire, 'EXPIRE', channelName]));
-                        }
-                    });
-                }
                 Server.send(userId, [0, HISTORY_KEEPER_ID, 'MSG', userId, JSON.stringify(metadata)]);
             }
 
@@ -859,7 +848,7 @@ HK.onDirectMessage = function (Env, Server, seq, userId, json) {
     // to stop people from loading history they shouldn't see.
     var channelName = parsed[1];
     nThen(function (w) {
-        HK.getMetadata(Env, channelName, w(function (err, metadata) {
+        getMetadata(Env, channelName, w(function (err, metadata) {
             if (err) {
                 // stream errors?
                 // we should log these, but if we can't load metadata
@@ -955,24 +944,16 @@ HK.onChannelMessage = function (Env, Server, channel, msgStruct) {
 
     let metadata;
     nThen(function (w) {
-        // getIndex (and therefore the latest metadata)
+        getMetadata(Env, channel.id, w(function (err, _metadata) {
-        getIndex(Env, channel.id, w(function (err, index) {
-            if (err) {
-                w.abort();
-                return void Log.error('CHANNEL_MESSAGE_ERROR', err);
-            }
-
-            if (!index.metadata) {
             // if there's no channel metadata then it can't be an expiring channel
             // nor can we possibly validate it
-                return;
+            if (!_metadata) { return; }
-            }
+            metadata = _metadata;
-
-            metadata = index.metadata;
 
             // don't write messages to expired channels
             if (checkExpired(Env, Server, channel)) { return void w.abort(); }
-
+        }));
+    }).nThen(function (w) {
         // if there's no validateKey present skip to the next block
         if (!metadata.validateKey) { return; }
 
@@ -994,7 +975,6 @@ HK.onChannelMessage = function (Env, Server, channel, msgStruct) {
             Log.info("HK_SIGNED_MESSAGE_REJECTED", 'Channel '+channel.id);
             return;
         }
-        }));
     }).nThen(function () {
         // do checkpoint stuff...