Remove command queue high and low water marks

Author: Ruben Bridgewater

README.md

@@ -154,11 +154,11 @@ So please attach the error listener to node_redis.
 `client` will emit `drain` when the TCP connection to the Redis server has been buffering, but is now
 writable. This event can be used to stream commands in to Redis and adapt to backpressure.
 
-All commands return a boolean if the stream had to buffer or not. If false is returned the stream had to buffer.
+If the stream is buffering `client.should_buffer` is set to true. Otherwise the variable is always set to false.
 That way you can decide when to reduce your send rate and resume sending commands when you get `drain`.
 
-You can manually control the low water and high water marks by passing ommand_queue_high_water` and `command_queue_low_water` to the client options.
-Check the [Node.js streams API](https://nodejs.org/api/stream.html) for further info.
+You can also check the return value of each command as it will also return the backpressure indicator.
+If false is returned the stream had to buffer.
 
 ### "idle"
 

changelog.md

@@ -10,6 +10,9 @@ Features
  -  using .multi / .batch (up to +50% / on Node.js 0.10.x +300%)
  -  saving small buffers
 -  Increased coverage to 99% ([@BridgeAR](https://github.com/BridgeAR))
+-  Refactored manual backpressure control ([@BridgeAR](https://github.com/BridgeAR))
+ -  Removed the high water mark and low water mark. Such a mechanism should be implemented by a user instead
+ -  The `drain` event is from now on only emitted if the stream really had to buffer
 
 Bugfixes
 

examples/backpressure_drain.js

@@ -1,10 +1,7 @@
 'use strict';
 
 var redis = require('../index'),
-    client = redis.createClient(null, null, {
-        command_queue_high_water: 5,
-        command_queue_low_water: 1
-    }),
+    client = redis.createClient(),
     remaining_ops = 100000, paused = false;
 
 function op() {
@@ -14,11 +11,12 @@ function op() {
     }
 
     remaining_ops--;
-    if (client.hset('test hash', 'val ' + remaining_ops, remaining_ops) === false) {
+    client.hset('test hash', 'val ' + remaining_ops, remaining_ops);
+    if (client.should_buffer === true) {
         console.log('Pausing at ' + remaining_ops);
         paused = true;
     } else {
-        process.nextTick(op);
+        setTimeout(op, 1);
     }
 }
 

examples/pub_sub.js

@@ -4,7 +4,7 @@ var redis = require('redis'),
     client1 = redis.createClient(), msg_count = 0,
     client2 = redis.createClient();
 
-// Most clients probably don't do much on 'subscribe'.  This example uses it to coordinate things within one program.
+// Most clients probably don't do much on 'subscribe'. This example uses it to coordinate things within one program.
 client1.on('subscribe', function (channel, count) {
     console.log('client1 subscribed to ' + channel + ', ' + count + ' total subscriptions');
     if (count === 2) {

index.js

@@ -82,8 +82,6 @@ function RedisClient(stream, options) {
         options.detect_buffers = false;
     }
     this.should_buffer = false;
-    this.command_queue_high_water = +options.command_queue_high_water || 1000;
-    this.command_queue_low_water = options.command_queue_low_water | 0;
     this.max_attempts = options.max_attempts | 0;
     this.command_queue = new Queue(); // Holds sent commands to de-pipeline them
     this.offline_queue = new Queue(); // Holds commands issued but not able to be sent

test/commands/keys.spec.js

@@ -15,8 +15,6 @@ describe("The 'keys' method", function () {
 
             beforeEach(function (done) {
                 args = args || {};
-                // This is going to test if the high water is also respected
-                args.command_queue_high_water = 100;
                 client = redis.createClient.apply(redis.createClient, args);
                 client.once("ready", function () {
                     client.flushdb(done);