Merge pull request #12 from ipfs/write-race

update dependencies and patch for racing condition

Author: daviddias

Diff for: .gitignore

@@ -1,5 +1,5 @@
 test/repo-just-for-test*
-
+test/test-repo-for-*
 # Logs
 logs
 *.log
@@ -35,4 +35,4 @@ node_modules
 .node_repl_history
 
 lib
-dist
+dist

Diff for: package.json

@@ -42,8 +42,8 @@
     "buffer-loader": "0.0.1",
     "chai": "^3.5.0",
     "fs-blob-store": "^5.2.1",
-    "idb-plus-blob-store": "^1.0.0",
-    "ipfs-repo": "^0.6.1",
+    "idb-plus-blob-store": "^1.1.1",
+    "ipfs-repo": "^0.6.6",
     "lodash": "^4.8.2",
     "ncp": "^2.0.0",
     "pre-commit": "^1.1.2",
@@ -60,4 +60,4 @@
     "Stephen Whitmore <stephen.whitmore@gmail.com>",
     "dignifiedquire <dignifiedquire@gmail.com>"
   ]
-}
+}

Diff for: src/block-service.js

@@ -14,12 +14,32 @@ function BlockService (ipfsRepo, exchange) {
     let done = false
 
     ws.write(block.data)
+
     ws.once('error', (err) => {
       done = true
       callback(err)
     })
+
     ws.once('finish', () => {
-      if (!done) callback()
+      if (!done) {
+        // Important to note: Writing to a stream
+        // isn't an atomic process, because streams can be
+        // piped, and the finish of one only represents that
+        // the data was buffered to the next one.
+        // This is something known and 'accepted' on the
+        // streams API, however, since we expose a callback
+        // interface on BlockService and a streams one,
+        // the users will expect for the callback to be fired
+        // when the final write was concluded. We add a
+        // timeout to ensure that.
+        // TODO: Create an elegant way to understand when
+        // the block was actually flushed to disk. This
+        // means changing how the blob-stores and repo are
+        // implemented.
+        // One option, is polling till we check it
+        // is written.
+        setTimeout(callback, 150)
+      }
     })
     ws.end()
   }

Diff for: test/block-service-test.js

@@ -29,7 +29,7 @@ module.exports = (repo) => {
     })
 
     it('store and get a block, with custom extension', (done) => {
-      const b = new Block('A random data block', 'ext')
+      const b = new Block('A random data block 2', 'ext')
       bs.addBlock(b, (err) => {
         expect(err).to.not.exist
         bs.getBlock(b.key, 'ext', (err, block) => {