From a8d709caf6ac815d69c9e8fd447fb87b5108ace8 Mon Sep 17 00:00:00 2001
From: Chris Kleeschulte <chrisk@bitpay.com>
Date: Tue, 8 Aug 2017 14:45:13 -0400
Subject: [PATCH] Added cache miss function for input values.

---
 lib/services/p2p/index.js               |  5 +-
 lib/services/transaction/index.js       | 62 +++++++++++++++++++++++--
 test/services/transaction/index.unit.js | 14 ++++++
 3 files changed, 73 insertions(+), 8 deletions(-)

diff --git a/lib/services/p2p/index.js b/lib/services/p2p/index.js
index 931246a3..7f43ba5e 100644
--- a/lib/services/p2p/index.js
+++ b/lib/services/p2p/index.js
@@ -202,8 +202,7 @@ P2P.prototype._hasPeers = function() {
 };
 
 P2P.prototype._initCache = function() {
-  this._inv = LRU(2000);
-  this._cache = [];
+  this._inv = LRU(1000);
 };
 
 P2P.prototype._initP2P = function() {
@@ -332,7 +331,7 @@ P2P.prototype._setResourceFilter = function(filter, resource) {
 };
 
 P2P.prototype._startBcoin = function() {
-  const network = ['livenet', 'live', 'main', 'mainnet'].indexOf(this.node.network) !== -1? 'main' : 'testnet' 
+  const network = ['livenet', 'live', 'main', 'mainnet'].indexOf(this.node.network) !== -1? 'main' : 'testnet';
   this._bcoin = new Bcoin({
     network: network,
     prefix: this.node.datadir
diff --git a/lib/services/transaction/index.js b/lib/services/transaction/index.js
index 8b9f4829..33b1f8eb 100644
--- a/lib/services/transaction/index.js
+++ b/lib/services/transaction/index.js
@@ -8,6 +8,8 @@ var _ = require('lodash');
 var LRU = require('lru-cache');
 var Unit = require('bitcore-lib').Unit;
 var log = require('../../index').log;
+var async = require('async');
+var assert = require('assert');
 
 function TransactionService(options) {
   BaseService.call(this, options);
@@ -16,7 +18,7 @@ function TransactionService(options) {
   this._block = this.node.services.block;
   this._p2p = this.node.services.p2p;
   this._timestamp = this.node.services.timestamp;
-  this._inputValuesCache = LRU(1E6); // this should speed up syncing
+  this._inputValuesCache = LRU(500000); // this should speed up syncing
 }
 
 inherits(TransactionService, BaseService);
@@ -48,9 +50,11 @@ TransactionService.prototype.getTransaction = function(txid, options, callback)
 
   var self = this;
 
+  var _tx;
   var queryMempool = _.isUndefined(options.queryMempool) ? true : options.queryMempool;
 
   var key = self.encoding.encodeTransactionKey(txid);
+
   self._db.get(key, function(err, tx) {
 
     if(err) {
@@ -67,9 +71,8 @@ TransactionService.prototype.getTransaction = function(txid, options, callback)
 
         if (memTx) {
           memTx.confirmations = 0;
-          return callback(null, memTx);
+          _tx = memTx;
         }
-        return callback();
 
       });
 
@@ -77,16 +80,61 @@ TransactionService.prototype.getTransaction = function(txid, options, callback)
 
       if (tx) {
         tx.confirmations = self._p2p.getBestHeight - tx.__height;
-        return callback(null,  tx);
+        _tx = tx;
       }
-      return callback();
 
     }
 
+    if (!_tx) {
+      return callback();
+    }
+
+    // TODO: this could cause crazy amounts of recursion if input values are missing from the entire chain of txs
+    self._addMissingInputValues(_tx, callback);
+
   });
 
 };
 
+TransactionService.prototype._addMissingInputValues = function(tx, callback) {
+
+  // if we have cache misses from when we populated input values,
+  // then we must go and find them after the fact (lazy-load).
+  var self = this;
+  async.eachOfLimit(tx.inputs, 4, function(input, index, next) {
+
+    var inputSatoshis = tx.__inputValues[index];
+
+    if (inputSatoshis >= 0) {
+      return next();
+    }
+
+    var outputIndex = input.prevout.index;
+    self.getTransaction(input.prevout.txid(), function(err, _tx) {
+
+      if (err || !_tx) {
+        return next(err || new Error('tx not found for tx id: ' + input.prevout.txid()));
+      }
+
+      var output = _tx.outputs[outputIndex];
+      assert(output, 'Expected an output, but did not get one for tx: ' + _tx.txid() + ' outputIndex: ' + outputIndex);
+      tx.__inputValues[index] = Unit.fromBTC(output.value).toSatoshis();
+      next();
+
+    });
+
+
+  }, function(err) {
+
+    if (err) {
+      return callback(err);
+    }
+
+    callback(null, tx);
+
+  });
+};
+
 TransactionService.prototype.sendTransaction = function(tx, callback) {
   this._p2p.sendTransaction(tx, callback);
 };
@@ -216,6 +264,10 @@ TransactionService.prototype._processTransaction = function(tx, opts) {
 
   // input values
   tx.__inputValues = this._getInputValues(tx); //if there are any nulls here, this is a cache miss
+  if (_.compact(tx.__inputValues).length < tx.inputs.length) {
+    log.debug('Transaction Service: Cache miss for tx id: ' + tx.txid());
+  }
+
   //timestamp
   tx.__timestamp = this._getBlockTimestamp(opts.block.rhash());
   //height
diff --git a/test/services/transaction/index.unit.js b/test/services/transaction/index.unit.js
index ad459a64..3f69d00e 100644
--- a/test/services/transaction/index.unit.js
+++ b/test/services/transaction/index.unit.js
@@ -122,4 +122,18 @@ describe('Transaction Service', function() {
     });
   });
 
+  describe('#_addMissingInputValues', function() {
+    it('should add missing input values on a tx', function(done) {
+      sandbox.stub(txService, 'getTransaction').callsArgWith(1, null, tx);
+      tx.__inputValues = [];
+      txService._addMissingInputValues(tx, function(err, tx) {
+        if (err) {
+          return done(err);
+        }
+        tx.__inputValues.should.deep.equal([113903300000000, 113903300000000, 50000000000000, 113903300000000 ]);
+        done();
+      });
+
+    });
+  });
 });