blockstore: optimize block read and index

There is potential for around a 10% to 23% increase to the performance
of block reads by using `allocUnsafe`, however there is already around
a 3 to 6 times increase to the performance. While it's safe to use
`allocUnsafe` as the number of bytes read is checked to be the same
size as the buffer allocation, there is a potential for test cases
to introduce _other_ behavior for `fs.read` that may not have the
same behavior, though this isn't currently the case.

lib/blockstore/file.js

@@ -11,8 +11,8 @@ const bdb = require('bdb');
 const assert = require('bsert');
 const fs = require('bfile');
 const bio = require('bufio');
+const hash256 = require('bcrypto/lib/hash256');
 const Network = require('../protocol/network');
-const Headers = require('../primitives/headers');
 const AbstractBlockStore = require('./abstract');
 const {BlockRecord, FileRecord} = require('./records');
 const layout = require('./layout');
@@ -130,10 +130,8 @@ class FileBlockStore extends AbstractBlockStore {
 
           if (type === types.BLOCK) {
             position = reader.offset;
-            const header = Headers.fromReader(reader);
-            hash = header.hash();
-            const read = reader.offset - position;
-            reader.seek(length - read);
+            hash = hash256.digest(reader.readBytes(80, true));
+            reader.seek(length - 80);
           } else {
             hash = reader.readHash();
             position = reader.offset;
@@ -271,7 +269,7 @@ class FileBlockStore extends AbstractBlockStore {
 
     const last = await this.db.get(layout.F.encode(type));
     if (last)
-      fileno = bio.read(last).readU32();
+      fileno = bio.readU32(last, 0);
 
     filepath = this.filepath(type, fileno);
 
@@ -482,9 +480,12 @@ class FileBlockStore extends AbstractBlockStore {
     const data = Buffer.alloc(length);
 
     const fd = await fs.open(filepath, 'r');
-    await fs.read(fd, data, 0, length, position);
+    const bytes = await fs.read(fd, data, 0, length, position);
     await fs.close(fd);
 
+    if (bytes !== length)
+      throw new Error('Wrong number of bytes read.');
+
     return data;
   }
 

test/blockstore-test.js

@@ -505,6 +505,55 @@ describe('BlockStore', function() {
         assert.equal(err.message, 'Could not write block.');
       });
     });
+
+    describe('read', function() {
+      const read = fs.read;
+      const open = fs.open;
+      const close = fs.close;
+      let get = null;
+      let raw = null;
+
+      before(() => {
+        const record = new BlockRecord({
+          file: 1,
+          position: 8,
+          length: 100
+        });
+        raw = record.toRaw();
+      });
+
+      beforeEach(() => {
+        get = store.db.get;
+      });
+
+      afterEach(() => {
+        // Restore stubbed methods.
+        store.db.get = get;
+        fs.read = read;
+        fs.open = open;
+        fs.close = close;
+      });
+
+      it('will error if total read bytes not correct', async () => {
+        let err = null;
+
+        store.db.get = () => raw;
+        fs.open = () => 7;
+        fs.close = () => undefined;
+        fs.read = () => 99;
+
+        try {
+          const hash = random.randomBytes(128);
+          const block = random.randomBytes(32);
+          await store.read(hash, block);
+        } catch (e) {
+          err = e;
+        }
+
+        assert(err, 'Expected error.');
+        assert.equal(err.message, 'Wrong number of bytes read.');
+      });
+    });
   });
 
   describe('FileBlockStore (Integration 1)', function() {