Fixed deferred search in Level-js/IndexedDB.

levelgraph · Jan 17, 2014 · 950d1e1 · 950d1e1
1 parent 8683aa1
commit 950d1e1
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Showing 5 changed files with 55 additions and 15 deletions.
diff --git a/lib/levelgraph.js b/lib/levelgraph.js
@@ -56,6 +56,8 @@ module.exports = function levelgraph(leveldb, options, readyCallback) {
 
   }
 
+  utilities.patchApproximateSize(leveldb);
+
   // it may be an empty object if we are on browserify.
   // we are not patching it up if a sublevel is passed in.
   if (typeof levelWriteStream === 'function' && leveldb.parent) {

diff --git a/lib/queryplanner.js b/lib/queryplanner.js
@@ -22,21 +22,15 @@ function queryplanner(db, options) {
 
     async.each(query, function(q, cb) {
       var newq = queryMask(q)
-        , range = utilities.createQuery(newq)
-        , result = function(err, size) {
-            if (err) {
-              return cb(err);
-            }
-            q.size = size;
-            async.nextTick(cb);
-          };
-
-      try {
-        db.approximateSize(range.start, range.end, result);
-      } catch(err) {
-        result(null, Object.keys(variablesMask(q)).length);
-      }
+        , range = utilities.createQuery(newq);
 
+      db.approximateSize(range.start, range.end, function(err, size) {
+        if (err) {
+          size = Object.keys(variablesMask(q)).length;
+        }
+        q.size = size;
+        async.nextTick(cb);
+      });
     }, function(err) {
       if (err) {
         callback(err);

diff --git a/lib/utilities.js b/lib/utilities.js
@@ -231,3 +231,36 @@ function matcher(pattern) {
 }
 
 module.exports.matcher = matcher;
+
+function patchApproximateSize(leveldb) {
+  // we need to be sublevel-aware
+  var db = leveldb.db || leveldb._root.db;
+
+  // monkey patching _approximateSize
+  // see https://github.com/maxogden/level.js/pull/21
+  function doPatch(db) {
+    if (db.constructor.name === 'Level') {
+      // we are in Level-js
+      db._approximateSize = function(a, b, callback) {
+        var err = new Error('Not implemented');
+        if (callback) {
+          return callback(err);
+        }
+
+        throw err;
+      };
+    }
+  }
+
+  if (db.constructor.name === 'DeferredLevelDOWN') {
+    db.setDb = function() {
+      doPatch(arguments[0]);
+      var result = db.constructor.prototype.setDb.apply(db, arguments);
+      return result;
+    };
+  } else {
+    doPatch(db);
+  }
+}
+
+module.exports.patchApproximateSize = patchApproximateSize;
diff --git a/test/queryplanner_spec.js b/test/queryplanner_spec.js
@@ -503,7 +503,11 @@ describe('query planner', function() {
 
   describe('without approximateSize', function() {
     beforeEach(function() {
-      db = {};
+      db = {
+        approximateSize: function(a, b, cb) {
+          cb(new Error('not implemented'));
+        }
+      };
       planner = queryplanner(db, { joinAlgorithm: 'sort' });
     });
 

diff --git a/test/triple_store_spec.js b/test/triple_store_spec.js
@@ -385,4 +385,11 @@ describe('deferred open support', function() {
       done();
     });
   });
+
+  it('should support deferred search', function(done) {
+    db = levelgraph(level());
+    db.search([{ predicate: 'likes' }], function() {
+      done();
+    });
+  });
 });