cached headers

lib/blockchain.js

@@ -9,6 +9,7 @@ var NULL = '0000000000000000000000000000000000000000000000000000000000000000';
 
 function BlockChain() {
   this.tip = NULL;
+  this.header = {};
   this.work = {};
   this.work[NULL] = 0;
   this.height = {};
@@ -18,6 +19,7 @@ function BlockChain() {
   };
   this.next = {};
   this.prev = {};
+  this.cachedHeaders = [];
 }
 
 BlockChain.NULL = NULL;
@@ -44,6 +46,7 @@ BlockChain.prototype.addData = function(header) {
   var prevHash = BufferUtil.reverse(header.prevHash).toString('hex');
   var hash = header.hash;
 
+  this.header[hash] = header;
   this.work[hash] = this.work[prevHash] + getWork(header.bits);
   this.prev[hash] = prevHash;
 };
@@ -112,6 +115,7 @@ BlockChain.prototype.confirm = function(hash) {
   this.next[prevHash] = hash;
   this.hashByHeight[height] = hash;
   this.height[hash] = height;
+  this.cachedHeaders.unshift(this.header[hash]);
 };
 
 BlockChain.prototype.unconfirm = function(hash) {
@@ -123,6 +127,7 @@ BlockChain.prototype.unconfirm = function(hash) {
   delete this.next[prevHash];
   delete this.hashByHeight[height];
   delete this.height[hash];
+  this.cachedHeaders.shift();
 };
 
 BlockChain.prototype.hasData = function(hash) {
@@ -178,4 +183,8 @@ BlockChain.prototype.getCurrentHeight = function() {
   return this.height[this.tip];
 };
 
+BlockChain.prototype.getHeaders = function() {
+  return this.cachedHeaders;
+};
+
 module.exports = BlockChain;

lib/node.js

@@ -128,6 +128,12 @@ BitcoreNode.prototype.initialize = function() {
           delete self.blockCache[deleteHash];
         }
       })
+      .then(function() {
+        // Update header cache every 100 blocks
+        if(block.height % 100 === 0) {
+          return self.blockService.saveHeaders(self.blockchain.getHeaders())
+        }
+      })
       .catch(function(error) {
         self.stop(error);
       });

lib/services/block.js

@@ -38,7 +38,8 @@ var Index = {
   height: 'bh-', // bh-<hash> -> height (-1 means disconnected)
   tip: 'tip', // tip -> { hash: hex, height: int }, the latest tip
   work: 'wk-', // wk-<hash> -> amount of work for block
-  header: 'header-' // header-<hash> -> JSON for block header
+  header: 'header-', // header-<hash> -> JSON for block header
+  headersCached: 'hc-'
 };
 _.extend(Index, {
   getNextBlock: helper(Index.next),
@@ -48,7 +49,7 @@ _.extend(Index, {
   getBlockByTs: function(block) {
     return Index.timestamp + block.header.time;
   },
-  getBlockHeader: helper(Index.header),
+  getBlockHeader: helper(Index.header)
 });
 
 function BlockService(opts) {
@@ -466,39 +467,63 @@ BlockService.prototype.getBlockchain = function() {
   var blockchain = new BlockChain();
   var headers = [];
 
-  console.log('Fetching headers from db...');
-  var fetchHeader = function(blockHash) {
-    if (blockHash === BlockChain.NULL) {
-      console.log('All headers fetched, total =', headers.length);
-      return;
-    }
-    var headerKey = Index.getBlockHeader(blockHash);
-    return self.database.getAsync(headerKey)
-      .then(function(json) {
-        return bitcore.Block.BlockHeader.fromJSON(json);
-      })
-      .then(function(header) {
-        headers.push(header);
-        return fetchHeader(BufferUtil.reverse(header.prevHash).toString('hex'));
-      });
-  };
+  console.log('Fetching hashes from db...');
 
-  return self._getLatestHash()
-    .then(function(tip) {
-      if (!tip) {
-        console.log('No tip found, syncing blockchain from genesis block');
-        return null;
+  return self.database.getAsync(Index.headersCached, {valueEncoding: 'json'})
+    .catch(function(err) {
+      if(err instanceof LevelUp.errors.NotFoundError) {
+        return [];
       }
-      console.log('Tip is', tip);
-      return fetchHeader(tip)
-        .then(function() {
-          while (headers.length !== 0) {
-            var header = headers.pop();
-            blockchain.proposeNewHeader(header);
+      throw err;
+    })
+    .then(function(cachedHeaders) {
+      console.log(cachedHeaders.length + ' headers cached');
+      cachedHeaders = cachedHeaders.map(function(json) {
+        return bitcore.Block.BlockHeader.fromJSON(json);
+      });
+      console.log('Cached headers parsed. Loading remaining headers from DB');
+
+      var fetchHeader = function(blockHash) {
+        if (blockHash === BlockChain.NULL) {
+          console.log('All headers fetched, total =', headers.length);
+          return Promise.resolve();
+        } else if(cachedHeaders[0] && cachedHeaders[0].hash === blockHash) {
+          headers = headers.concat(cachedHeaders);
+          return Promise.resolve();
+        }
+        var headerKey = Index.getBlockHeader(blockHash);
+        return self.database.getAsync(headerKey)
+          .then(function(json) {
+            return bitcore.Block.BlockHeader.fromJSON(json);
+          })
+          .then(function(header) {
+            headers.push(header);
+            return fetchHeader(BufferUtil.reverse(header.prevHash).toString('hex'));
+          });
+      };
+
+      return self._getLatestHash()
+        .then(function(tip) {
+          if (!tip) {
+            console.log('No tip found, syncing blockchain from genesis block');
+            return null;
           }
-          return blockchain;
-        });
+          console.log('Tip is', tip);
+
+          return fetchHeader(tip)
+            .then(function() {
+              while (headers.length !== 0) {
+                var header = headers.pop();
+                blockchain.proposeNewHeader(header);
+              }
+              return blockchain;
+            });
+        })
     });
 };
 
+BlockService.prototype.saveHeaders = function(headers) {
+  return this.database.putAsync(Index.headersCached, JSON.stringify(headers));
+}
+
 module.exports = BlockService;