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Make WMS server selection deterministic, by using a real number hashing algorithm on the parameter string to select the server URL. Also, patch TMS since it doesn't use getFullParameterString(). Passes all tests. Fixes #410.

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git-svn-id: http://svn.openlayers.org/trunk/openlayers@2821 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Schuyler Erle
2007-03-20 00:00:17 +00:00
parent 40a7cd881c
commit 15b26252bc
4 changed files with 61 additions and 12 deletions
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32
lib/OpenLayers/Layer/HTTPRequest.js
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@@ -90,6 +90,18 @@ OpenLayers.Layer.HTTPRequest.prototype =
this.params = OpenLayers.Util.extend(this.params, newParams);
},
/**
* @param {String} paramString
* @param {Array(String)} urls
*/
selectUrl: function(paramString, urls) {
var product = 1;
for (var i = 0; i < paramString.length; i++) {
product *= paramString.charCodeAt(i) * (Math.sqrt(5) - 1) / Math.sqrt(3);
product -= Math.floor(product);
}
return urls[Math.floor(product * urls.length)];
},
/** combine url with layer's params and these newParams.
*
@@ -109,15 +121,6 @@ OpenLayers.Layer.HTTPRequest.prototype =
// use layer's url unless altUrl passed in
var url = (altUrl == null) ? this.url : altUrl;
// if url is not a string, it should be an array of strings,
// in which case we will randomly select one of them in order
// to evenly distribute requests to different urls.
if (typeof url == "object") {
url = url[Math.floor(Math.random()*url.length)];
}
// requestString always starts with url
var requestString = url;
// create a new params hashtable with all the layer params and the
// new params together. then convert to string
var allParams = OpenLayers.Util.extend(new Object(), this.params);
@@ -131,6 +134,17 @@ OpenLayers.Layer.HTTPRequest.prototype =
}
}
var paramsString = OpenLayers.Util.getParameterString(allParams);
// if url is not a string, it should be an array of strings,
// in which case we will deterministically select one of them in
// order to evenly distribute requests to different urls.
if (url instanceof Array) {
url = this.selectUrl(paramsString, url);
}
// requestString always starts with url
var requestString = url;
if (paramsString != "") {
var lastServerChar = url.charAt(url.length - 1);
if ((lastServerChar == "&") || (lastServerChar == "?")) {

7
lib/OpenLayers/Layer/TMS.js
View File

@@ -75,7 +75,12 @@ OpenLayers.Layer.TMS.prototype =
var x = (bounds.left - this.tileOrigin.lon) / (res * this.tileSize.w);
var y = (bounds.bottom - this.tileOrigin.lat) / (res * this.tileSize.h);
var z = this.map.getZoom();
return this.url + "1.0.0" + "/" + this.layername + "/" + z + "/" + x + "/" + y + "." + this.type;
var path = "1.0.0" + "/" + this.layername + "/" + z + "/" + x + "/" + y + "." + this.type;
var url = this.url;
if (url instanceof Array) {
url = this.selectUrl(path, url);
}
return url + path;
},
/**