Merge pull request #323 from peakji/master

Multiple seeks in ltgt range and support Buffers

README.md

@@ -224,7 +224,8 @@ the `callback` function will be called with no arguments in any of the following
 
 * the iterator comes to the end of the store
 * the `end` key has been reached; or
-* the `limit` has been reached
+* the `limit` has been reached; or
+* the last `seek()` was out of range
 
 Otherwise, the `callback` function will be called with the following 3 arguments:
 

iterator.js

@@ -14,11 +14,20 @@ function Iterator (db, options) {
 
 util.inherits(Iterator, AbstractIterator)
 
-Iterator.prototype.seek = function (key) {
-  if (typeof key !== 'string')
-    throw new Error('seek requires a string key')
+Iterator.prototype.seek = function (target) {
+  if (this._ended)
+    throw new Error('cannot call seek() after end()')
+  if (this._nexting)
+    throw new Error('cannot call seek() before next() has completed')
+
+  if (typeof target !== 'string' && !Buffer.isBuffer(target))
+    throw new Error('seek() requires a string or buffer key')
+  if (target.length == 0)
+    throw new Error('cannot seek() to an empty key')
+
   this.cache = null
-  this.binding.seek(key)
+  this.binding.seek(target)
+  this.finished = false
 }
 
 Iterator.prototype._next = function (callback) {

package.json

@@ -39,6 +39,8 @@
     "delayed": "~1.0.1",
     "du": "~0.1.0",
     "faucet": "0.0.1",
+    "iota-array": "~1.0.0",
+    "lexicographic-integer": "~1.1.0",
     "mkfiletree": "~1.0.1",
     "monotonic-timestamp": "~0.0.8",
     "node-uuid": "~1.4.3",

src/iterator.cc

@@ -56,6 +56,7 @@ Iterator::Iterator (
   options->snapshot = database->NewSnapshot();
   dbIterator = NULL;
   count      = 0;
+  target     = NULL;
   seeking    = false;
   nexting    = false;
   ended      = false;
@@ -64,6 +65,7 @@ Iterator::Iterator (
 
 Iterator::~Iterator () {
   delete options;
+  ReleaseTarget();
   if (start != NULL) {
     // Special case for `start` option: it won't be
     // freed up by any of the delete calls below.
@@ -171,6 +173,38 @@ bool Iterator::Read (std::string& key, std::string& value) {
   return false;
 }
 
+bool Iterator::OutOfRange (leveldb::Slice* target) {
+  if (lt != NULL) {
+    if (target->compare(*lt) >= 0)
+      return true;
+  } else if (lte != NULL) {
+    if (target->compare(*lte) > 0)
+      return true;
+  } else if (start != NULL && reverse) {
+    if (target->compare(*start) > 0)
+      return true;
+  }
+
+  if (end != NULL) {
+    int d = target->compare(*end);
+    if (reverse ? d < 0 : d > 0)
+      return true;
+  }
+
+  if (gt != NULL) {
+    if (target->compare(*gt) <= 0)
+      return true;
+  } else if (gte != NULL) {
+    if (target->compare(*gte) < 0)
+      return true;
+  } else if (start != NULL && !reverse) {
+    if (target->compare(*start) < 0)
+      return true;
+  }
+
+  return false;
+}
+
 bool Iterator::IteratorNext (std::vector<std::pair<std::string, std::string> >& result) {
   size_t size = 0;
   while(true) {
@@ -205,7 +239,19 @@ void Iterator::Release () {
   database->ReleaseIterator(id);
 }
 
+void Iterator::ReleaseTarget () {
+  if (target != NULL) {
+
+    if (!target->empty())
+      delete[] target->data();
+
+    delete target;
+    target = NULL;
+  }
+}
+
 void checkEndCallback (Iterator* iterator) {
+  iterator->ReleaseTarget();
   iterator->nexting = false;
   if (iterator->endWorker != NULL) {
     Nan::AsyncQueueWorker(iterator->endWorker);
@@ -215,35 +261,52 @@ void checkEndCallback (Iterator* iterator) {
 
 NAN_METHOD(Iterator::Seek) {
   Iterator* iterator = Nan::ObjectWrap::Unwrap<Iterator>(info.This());
+
+  iterator->ReleaseTarget();
+
+  v8::Local<v8::Value> targetBuffer = info[0].As<v8::Value>();
+  LD_STRING_OR_BUFFER_TO_COPY(_target, targetBuffer, target);
+  iterator->target = new leveldb::Slice(_targetCh_, _targetSz_);
+
   iterator->GetIterator();
   leveldb::Iterator* dbIterator = iterator->dbIterator;
-  Nan::Utf8String key(info[0]);
 
-  dbIterator->Seek(*key);
+  dbIterator->Seek(*iterator->target);
   iterator->seeking = true;
 
-  if (dbIterator->Valid()) {
-    int cmp = dbIterator->key().compare(*key);
-    if (cmp > 0 && iterator->reverse) {
-      dbIterator->Prev();
-    } else if (cmp < 0 && !iterator->reverse) {
-      dbIterator->Next();
-    }
-  } else {
+  if (iterator->OutOfRange(iterator->target)) {
     if (iterator->reverse) {
-      dbIterator->SeekToLast();
-    } else {
       dbIterator->SeekToFirst();
+      dbIterator->Prev();
+    } else {
+      dbIterator->SeekToLast();
+      dbIterator->Next();
     }
+  }
+  else {
     if (dbIterator->Valid()) {
-      int cmp = dbIterator->key().compare(*key);
+      int cmp = dbIterator->key().compare(*iterator->target);
       if (cmp > 0 && iterator->reverse) {
-        dbIterator->SeekToFirst();
         dbIterator->Prev();
       } else if (cmp < 0 && !iterator->reverse) {
-        dbIterator->SeekToLast();
         dbIterator->Next();
       }
+    } else {
+      if (iterator->reverse) {
+        dbIterator->SeekToLast();
+      } else {
+        dbIterator->SeekToFirst();
+      }
+      if (dbIterator->Valid()) {
+        int cmp = dbIterator->key().compare(*iterator->target);
+        if (cmp > 0 && iterator->reverse) {
+          dbIterator->SeekToFirst();
+          dbIterator->Prev();
+        } else if (cmp < 0 && !iterator->reverse) {
+          dbIterator->SeekToLast();
+          dbIterator->Next();
+        }
+      }
     }
   }
 

src/iterator.h

@@ -53,13 +53,15 @@ class Iterator : public Nan::ObjectWrap {
   leveldb::Status IteratorStatus ();
   void IteratorEnd ();
   void Release ();
+  void ReleaseTarget ();
 
 private:
   Database* database;
   uint32_t id;
   leveldb::Iterator* dbIterator;
   leveldb::ReadOptions* options;
   leveldb::Slice* start;
+  leveldb::Slice* target;
   std::string* end;
   bool seeking;
   bool reverse;
@@ -83,6 +85,7 @@ class Iterator : public Nan::ObjectWrap {
 private:
   bool Read (std::string& key, std::string& value);
   bool GetIterator ();
+  bool OutOfRange (leveldb::Slice* target);
 
   static NAN_METHOD(New);
   static NAN_METHOD(Seek);