cache last fee level

lib/server.js

@@ -1148,6 +1148,7 @@ WalletService.prototype.getBalance = function(opts, cb) {
   });
 };
 
+
 WalletService.prototype._sampleFeeLevels = function(network, points, cb) {
   var self = this;
 
@@ -1169,13 +1170,15 @@ WalletService.prototype._sampleFeeLevels = function(network, points, cb) {
 
     if (failed.length) {
       var logger = network == 'livenet' ? log.warn : log.debug;
-      logger('Could not compute fee estimation in ' + network + ': ' + failed.join(','));
+      logger('Could not compute fee estimation in ' + network + ': ' + failed.join(', ') + ' blocks.');
     }
 
     return cb(null, levels);
   });
 };
 
+WalletService._feeLevelCache = {};
+
 /**
  * Returns fee levels for the current state of the network.
  * @param {Object} opts
@@ -1191,6 +1194,8 @@ WalletService.prototype.getFeeLevels = function(opts, cb) {
   if (network != 'livenet' && network != 'testnet')
     return cb(new ClientError('Invalid network'));
 
+  var cache = WalletService._feeLevelCache[network] || {};
+
   var levels = Defaults.FEE_LEVELS;
   var samplePoints = _.uniq(_.pluck(levels, 'nbBlocks'));
   self._sampleFeeLevels(network, samplePoints, function(err, feeSamples) {
@@ -1199,8 +1204,13 @@ WalletService.prototype.getFeeLevels = function(opts, cb) {
         level: level.name,
       };
       if (err || feeSamples[level.nbBlocks] < 0) {
+        if (cache[level.nbBlocks] >= 0) {
+          result.feePerKb = cache[level.nbBlocks];
+          result.nbBlocks = level.nbBlocks;
+        } else {
           result.feePerKb = level.defaultValue;
           result.nbBlocks = null;
+        }
       } else {
         result.feePerKb = feeSamples[level.nbBlocks];
         result.nbBlocks = level.nbBlocks;
@@ -1208,6 +1218,14 @@ WalletService.prototype.getFeeLevels = function(opts, cb) {
       return result;
     });
 
+    var obtainedValues = _.zipObject(_.map(_.reject(values, {
+      nbBlocks: null
+    }), function(v) {
+      return [v.nbBlocks, v.feePerKb];
+    }));
+
+    WalletService._feeLevelCache[network] = _.assign(cache, obtainedValues);
+
     return cb(null, values);
   });
 };

test/integration/server.js

@@ -1823,6 +1823,7 @@ describe('Wallet service', function() {
       helpers.createAndJoinWallet(1, 1, function(s, w) {
         server = s;
         wallet = w;
+        WalletService._feeLevelCache = {};
         done();
       });
     });
@@ -1887,6 +1888,48 @@ describe('Wallet service', function() {
         done();
       });
     });
+    it('should get cached value if network cannot estimate but an estimation was retrieved previously', function(done) {
+      helpers.stubFeeLevels({
+        1: 40000,
+        2: 20000,
+        6: 18000,
+      });
+      server.getFeeLevels({}, function(err, fees) {
+        should.not.exist(err);
+        fees = _.zipObject(_.map(fees, function(item) {
+          return [item.level, item];
+        }));
+        fees.priority.feePerKb.should.equal(40000);
+        fees.priority.nbBlocks.should.equal(1);
+
+        fees.normal.feePerKb.should.equal(20000);
+        fees.normal.nbBlocks.should.equal(2);
+
+        fees.economy.feePerKb.should.equal(18000);
+        fees.economy.nbBlocks.should.equal(6);
+
+        helpers.stubFeeLevels({
+          1: -1,
+          2: 25000,
+          6: 10000,
+        });
+        server.getFeeLevels({}, function(err, fees) {
+          should.not.exist(err);
+          fees = _.zipObject(_.map(fees, function(item) {
+            return [item.level, item];
+          }));
+          fees.priority.feePerKb.should.equal(40000);
+          fees.priority.nbBlocks.should.equal(1);
+
+          fees.normal.feePerKb.should.equal(25000);
+          fees.normal.nbBlocks.should.equal(2);
+
+          fees.economy.feePerKb.should.equal(10000);
+          fees.economy.nbBlocks.should.equal(6);
+          done();
+        });
+      });
+    });
   });
 
   describe('Wallet not complete tests', function() {