tilelive-mapnik image pool

image-pool.diff

diff --git a/lib/render.js b/lib/render.js
index cd74f80..dec3af2 100644
--- a/lib/render.js
+++ b/lib/render.js
@@ -1,6 +1,7 @@
 var mapnik = require('mapnik');
 var _ = require('underscore');
 var Step = require('step');
+var Pool = require('generic-pool').Pool;
 
 var MapnikSource = require('./mapnik_backend');
 var solidCache = {};
@@ -11,6 +12,53 @@ var EARTH_CIRCUMFERENCE = EARTH_DIAMETER * Math.PI;
 var MAX_RES = EARTH_CIRCUMFERENCE / 256;
 var ORIGIN_SHIFT = EARTH_CIRCUMFERENCE/2;
 
+var image_pools = function(size) {
+    return {
+        max: size || 5,
+        pools: {},
+        acquire: function(id, options, callback) {
+            if (!this.pools[id]) {
+                var that = this;
+                this.pools[id] = Pool({
+                    name: id,
+                    create: function(cb) { cb(null,new mapnik.Image(id,id)) },
+                    destroy: function(obj) { delete obj },
+                    max: that.max,
+                    idleTimeoutMillis: options.idleTimeoutMillis || 5000,
+                    log: false
+                    //reapIntervalMillis
+                    //priorityRange
+                });
+            }
+            this.pools[id].acquire(callback, options.priority || 0);
+        },
+        release: function(id, obj) {
+            var p = this.pools[id];
+            if (p) {
+                p.release(obj);
+                if (p.waitingClientsCount() > 0) {
+                    console.log(id + ': pool size: ' + p.getPoolSize());
+                    console.log(id + ': available: ' + p.availableObjectsCount());
+                    console.log(id + ': waiting  : ' + p.waitingClientsCount());
+                }
+                // todo - cleanup unused pool for a given id
+            }
+        },
+        drain: function() {
+            for (obj in this.pools) {
+                var p = this.pools[obj];
+                p.drain(function () {
+                    p.destroyAllNow(function() {
+                    });
+                });
+            };
+        }
+    };
+};
+
+var images = image_pools(20);
+//Math.ceil(Math.max(10, require('os').cpus().length * 2))
+
 
 exports['calculateMetatile'] = calculateMetatile;
 function calculateMetatile(options) {
@@ -119,58 +167,88 @@ MapnikSource.prototype._renderMetatile = function(options, callback) {
 
     // Calculate bbox from xyz, respecting metatile settings.
     var meta = calculateMetatile(options);
-
-    // Set default options.
-    if (options.format === 'utf') {
-        options.layer = source._info.interactivity_layer;
-        options.fields = source._info.interactivity_fields;
-        options.resolution = source._uri.query.resolution;
-        options.headers = { 'Content-Type': 'text/javascript; charset=utf-8' };
-        var image = new mapnik.Grid(meta.width, meta.height);
-    } else {
-        options.headers = { 'Content-Type': 'image/png' };
-        if (options.format.indexOf('jpeg') != -1) {
-            options.headers = { 'Content-Type': 'image/jpeg' };
-        }
-        var image = new mapnik.Image(meta.width, meta.height);
-    }
-
     options.scale = source._uri.query.scale;
-
     // Add reference to the source allowing debug/stat reporting to be compiled.
     options.source = source;
 
     process.nextTick(function() {
         source._pool.acquire(function(err, map) {
             if (err) return callback(err);
-
             // Begin at metatile boundary.
             options.x = meta.x;
             options.y = meta.y;
-
             map.resize(meta.width, meta.height);
+            //console.log('w: ' + meta.width + " h: " + meta.height);
             map.extent = meta.bbox;
 
-            try {
-                source._stats.render++;
-                map.render(image, options, function(err, image) {
-                    process.nextTick(function() {
-                        // Release after the .render() callback returned
-                        // to avoid mapnik errors.
-                        source._pool.release(map);
+            // Set default options.
+            if (options.format === 'utf') {
+                options.layer = source._info.interactivity_layer;
+                options.fields = source._info.interactivity_fields;
+                options.resolution = source._uri.query.resolution;
+                options.headers = { 'Content-Type': 'text/javascript; charset=utf-8' };
+                var image = new mapnik.Grid(meta.width, meta.height);
+                try {
+                    source._stats.render++;
+                    map.render(image, options, function(err, image) {
+                        process.nextTick(function() {
+                            // Release after the .render() callback returned
+                            // to avoid mapnik errors.
+                            source._pool.release(map);
+                        });
+                        if (err) return callback(err);
+                        if (meta.tiles.length > 1) {
+                            sliceMetatile(image, options, meta, callback);
+                        } else {
+                            encodeSingleTile(image, options, meta, callback);
+                        }
                     });
+                } catch(err) {
+                    source._pool.release(map);
+                    callback(err);
+                }
 
-                    if (err) return callback(err);
-
-                    if (meta.tiles.length > 1) {
-                        sliceMetatile(image, options, meta, callback);
-                    } else {
-                        encodeSingleTile(image, options, meta, callback);
+            } else {
+                options.headers = { 'Content-Type': 'image/png' };
+                if (options.format.indexOf('jpeg') != -1) {
+                    options.headers = { 'Content-Type': 'image/jpeg' };
+                }
+                images.acquire(meta.width,{},function(err,image) {
+                    if (err) {
+                        images.release(meta.width,image);
+                        return callback(err);
+                    }
+                    if (image.reused) {
+                        image.clear();
+                    }
+                    image.reused = true;
+                    try {
+                        source._stats.render++;
+                        map.render(image, options, function(err, image) {
+                            process.nextTick(function() {
+                                // Release after the .render() callback returned
+                                // to avoid mapnik errors.
+                                source._pool.release(map);
+                            });
+                            if (err) return callback(err);
+                            if (meta.tiles.length > 1) {
+                                sliceMetatile(image, options, meta, function(err,tiles) {
+                                    images.release(meta.width,image);
+                                    callback(err,tiles);
+                                });
+                            } else {
+                                encodeSingleTile(image, options, meta, function(err,tiles) {
+                                    images.release(meta.width,image);
+                                    callback(err,tiles);
+                                });
+                            }
+                        });
+                    } catch(err) {
+                        source._pool.release(map);
+                        images.release(meta.width,image);
+                        callback(err);
                     }
                 });
-            } catch(err) {
-                source._pool.release(map);
-                callback(err);
             }
         });
     });