001package votorola.a.count.gwt; // Copyright 2011-2012, Michael Allan. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Votorola Software"), to deal in the Votorola Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicence, and/or sell copies of the Votorola Software, and to permit persons to whom the Votorola Software is furnished to do so, subject to the following conditions: The preceding copyright notice and this permission notice shall be included in all copies or substantial portions of the Votorola Software. THE VOTOROLA SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE VOTOROLA SOFTWARE OR THE USE OR OTHER DEALINGS IN THE VOTOROLA SOFTWARE. 002 003import com.google.gwt.core.client.JavaScriptObject; 004import com.google.gwt.http.client.URL; 005import com.google.gwt.jsonp.client.JsonpRequest; 006import com.google.gwt.user.client.rpc.AsyncCallback; 007import java.util.HashMap; 008import votorola.a.web.gwt.*; 009import votorola.a.web.wap.*; 010import votorola.g.web.gwt.*; 011 012 013/** A cache of counts on the client side. 014 */ 015public final class CountCache 016{ 017 018 019 /** The single instance of CountCache. 020 */ 021 public static CountCache i() { return instance; } 022 023 024 private static CountCache instance; 025 026 { // constructed by CountMod 027 if( instance != null ) throw new IllegalStateException(); 028 029 instance = CountCache.this; 030 } 031 032 033 034 // ------------------------------------------------------------------------------------ 035 036 037 /** Appends the common portion of a {@linkplain votorola.s.wap.CountWAP CountWAP} 038 * request to the string builder. 039 */ 040 static void appendRequestLoc( final String pollName, final StringBuilder b ) 041 { 042 b.append( App.getServletContextLocation() ); 043 b.append( "/wap?wCall=cCount&cPoll=" ).append( URL.encodeQueryString( pollName )); 044 b.append( "&wNonce=" ).append( URLX.serialNonce() ); 045 } 046 047 048 049 /** Requests a count from the remote count engine and stores a record of the request 050 * in this cache. 051 * 052 * @see #requestCount_loc(String,StringBuilder) 053 */ 054 public JsonpRequest<WAPResponse> requestCount( final String pollName, final String loc, 055 final AsyncCallback<CountJS> callback ) 056 { 057 assert requestRecord(pollName) == null: "count requests not repeated"; 058 return App.i().jsonpWAP().requestObject( loc, new WAPCleanCallback( pollName ) 059 { 060 public void onFailure( final Throwable x ) 061 { 062 final RequestRecord r = requestMap.put( pollName, new RequestRecord() ); 063 if( r != null ) // collision with another request 064 { 065 requestMap.put( pollName, r ); // put it back instead of clobbering it 066 final CountJS count = r.count(); 067 if( count != null ) 068 { 069 callback.onSuccess( count ); 070 return; 071 } 072 } 073 074 callback.onFailure( x ); 075 } 076 077 public void onSuccess( final WAPResponseP responseP ) 078 { 079 CountJS count = responseP.cast(); 080 final RequestRecord r = requestMap.put( pollName, new RequestRecord( count )); 081 if( r != null ) // collision with another request 082 { 083 final CountJS countOld = r.count(); 084 if( countOld != null ) 085 { 086 requestMap.put( pollName, r ); // put it back instead of clobbering it 087 callback.onSuccess( countOld ); 088 return; 089 } 090 // else no harm in clobbering it 091 } 092 count.init( pollName ); 093 callback.onSuccess( count ); 094 } 095 }); 096 } 097 098 099 100 /** Appends the location for calls to <code>requestCount</code> and returns the string 101 * builder. 102 */ 103 public static StringBuilder requestCount_loc( final String pollName, final StringBuilder b ) 104 { 105 appendRequestLoc( pollName, b ); 106 b.append( "&cBase" ); 107 return b; 108 } 109 110 111 112 /** Returns a cached record of a count request, or null if no record is cached. 113 */ 114 public RequestRecord requestRecord( final String pollName ) 115 { 116 return requestMap.get( pollName ); 117 } 118 119 120 121 // ==================================================================================== 122 123 124 /** A cached record of a count request. 125 */ 126 public static final class RequestRecord 127 { 128 129 RequestRecord() { count = null; } 130 131 132 RequestRecord( final CountJS _count ) { count = _count; } 133 134 135 /** The count, or null if the request failed. At present no information 136 * concerning the cause of a failure is recorded. 137 */ 138 public CountJS count() { return count; } 139 140 141 private final CountJS count; 142 143 144 } 145 146 147 148 // ==================================================================================== 149 150 151 /** A response from the {@linkplain votorola.s.wap.CountWAP CountWAP} API. 152 */ 153 public static final class WAPResponse extends JavaScriptObject 154 { 155 156 protected WAPResponse() {} // "precisely one constructor... protected, empty, and no-argument" 157 158 159 WAPResponseP forPoll( final String pollName ) throws WAPException 160 { 161 final WAPResponseP responseP = _forPoll( pollName ); 162 if( responseP == null ) 163 { 164 throw new WAPException( "malformed response, missing count data for poll \"" 165 + pollName + "\"" ); 166 } 167 168 return responseP; 169 } 170 171 172 private native WAPResponseP _forPoll( final String pollName ) 173 /*-{ 174 return this.c.poll[pollName]; 175 }-*/; 176 177 } 178 179 180 181 // ==================================================================================== 182 183 184 /** A particular poll in a response from the count engine's Web API. 185 */ 186 static final class WAPResponseP extends JavaScriptObject 187 { 188 189 protected WAPResponseP() {} // "precisely one constructor... protected, empty, and no-argument" 190 191 192 void ensureClean() throws WAPException 193 { 194 final String errorSummary = summarizeError(); 195 if( errorSummary != null ) throw new WAPException( errorSummary ); 196 } 197 198 199 /** Either constructs a summary of the error report, or returns null if no error 200 * was reported. 201 */ 202 native String summarizeError() 203 /*-{ 204 if( !this.error ) return null; 205 206 var s = ""; 207 for( var name in this.error ) 208 { 209 if( s ) s += ", "; 210 s += name; 211 } 212 return s; 213 }-*/; 214 215 216 } 217 218 219 220//// P r i v a t e /////////////////////////////////////////////////////////////////////// 221 222 223 private static final HashMap<String,RequestRecord> requestMap = 224 new HashMap<String,RequestRecord>(); 225 226 227 228}