eclipse-sailing-analytics/sailing-analytics
1
0
Fork 0
mirror of https://github.com/eclipse-sailing-analytics/sailing-analytics.git synced 2026-09-19 20:25:31 +00:00
Code Activity

switched Leaderboard JSON cache from caching JSONObject to StringBuffer which saves repeated JSON to String serialization

Browse Source
This commit is contained in:
Axel Uhl
2013-05-18 02:01:20 +02:00
parent bf89d0e6fd
commit c442833075
1 changed files with 42 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
java/com.sap.sailing.server.gateway/src/com/sap/sailing/server/gateway/impl/LeaderboardJsonGetServlet.java
+42 -23
View File
@@ -1,6 +1,7 @@
package com.sap.sailing.server.gateway.impl;
import java.io.IOException;
import java.io.StringWriter;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
@@ -64,13 +65,13 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
private int cacheMisses;
/**
* The cache values are linked hash maps keeping the rendered JSON objects per time point/result state pair. The cache uses
* The cache values are linked hash maps keeping the rendered JSON objects as String per time point/result state pair. The cache uses
* a <em>linked</em> hash map because this way old values can be evicted easily, keeping the cache below a maximum size.
* Also, typing the {@link SmartFutureCache} with {@link LinkedHashMap} instead of only {@link Map} ensures that also when
* computing cache updates, new values are appended "at the end" and therefore tend to survive longer than any value appended
* earlier.
*/
private final SmartFutureCache<Leaderboard, LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject>, LeaderboardJsonCacheUpdateInterval> cache;
private final SmartFutureCache<Leaderboard, LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer>, LeaderboardJsonCacheUpdateInterval> cache;
/**
* Used to observe the leaderboards cached so far and triggering {@link #cache} updates.
@@ -106,38 +107,42 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
}
private class LeaderboardJsonCacheUpdater implements CacheUpdater<Leaderboard, LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject>, LeaderboardJsonCacheUpdateInterval> {
private class LeaderboardJsonCacheUpdater
implements
CacheUpdater<Leaderboard, LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer>, LeaderboardJsonCacheUpdateInterval> {
@Override
public LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> computeCacheUpdate(Leaderboard key,
public LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> computeCacheUpdate(Leaderboard key,
LeaderboardJsonCacheUpdateInterval updateInterval) throws Exception {
final LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> result;
final LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> result;
if (updateInterval == null) {
result = null;
} else {
result = new LinkedHashMap<>();
for (Pair<TimePoint, ResultStates> timePointAndResultState : updateInterval.getTimePointsAndResultStates()) {
result.put(timePointAndResultState, computeLeaderboardJson(key, timePointAndResultState));
StringWriter sw = new StringWriter();
computeLeaderboardJson(key, timePointAndResultState).writeJSONString(sw);
result.put(timePointAndResultState, sw.getBuffer());
}
}
return result;
}
@Override
public LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> provideNewCacheValue(Leaderboard leaderboard,
LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> oldCacheValue,
LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> computedCacheUpdate,
public LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> provideNewCacheValue(Leaderboard leaderboard,
LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> oldCacheValue,
LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> computedCacheUpdate,
LeaderboardJsonCacheUpdateInterval updateInterval) {
final LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> result;
final LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> result;
if (computedCacheUpdate == null) {
result = null;
if (oldCacheValue != null) {
totalNumberOfCacheEntries -= oldCacheValue.size();
}
} else {
result = new LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject>() {
result = new LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer>() {
private static final long serialVersionUID = -6197983565575024084L;
@Override
protected boolean removeEldestEntry(Entry<Pair<TimePoint, ResultStates>, JSONObject> eldest) {
protected boolean removeEldestEntry(Entry<Pair<TimePoint, ResultStates>, StringBuffer> eldest) {
final boolean result;
if (totalNumberOfCacheEntries > MAX_TOTAL_NUMBER_OF_CACHE_ENTRIES) {
totalNumberOfCacheEntries--;
@@ -187,20 +192,33 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
try {
ResultStates resultState = resolveRequestedResultState(req.getParameter(PARAM_NAME_RESULTSTATE));
TimePoint resultTimePoint = calculateTimePointForResultState(leaderboard, resultState);
JSONObject jsonLeaderboard;
StringBuffer jsonLeaderboardAsString;
if (resultTimePoint != null) {
Pair<TimePoint, ResultStates> resultStateAndTimePoint = new Pair<>(resultTimePoint, resultState);
if (useCache) {
jsonLeaderboard = getLeaderboardJsonFromCacheOrCompute(leaderboard, resultStateAndTimePoint, requestTimePoint);
jsonLeaderboardAsString = getLeaderboardJsonFromCacheOrCompute(leaderboard, resultStateAndTimePoint, requestTimePoint);
} else {
jsonLeaderboard = computeLeaderboardJson(leaderboard, resultStateAndTimePoint);
StringWriter sw = new StringWriter();
computeLeaderboardJson(leaderboard, resultStateAndTimePoint).writeJSONString(sw);
jsonLeaderboardAsString = sw.getBuffer();
}
} else {
jsonLeaderboard = createEmptyLeaderboardJson(leaderboard, resultState, requestTimePoint);
StringWriter sw = new StringWriter();
createEmptyLeaderboardJson(leaderboard, resultState, requestTimePoint).writeJSONString(sw);
jsonLeaderboardAsString = sw.getBuffer();
}
jsonLeaderboard.put("requestTimepoint", requestTimePoint.toString());
setJsonResponseHeader(resp);
jsonLeaderboard.writeJSONString(resp.getWriter());
synchronized (jsonLeaderboardAsString) {
int indexOfFirstOpeningBrace = jsonLeaderboardAsString.indexOf("{");
final String requestTimePointAsJson = "\"requestTimepoint\": \""+requestTimePoint.toString()+"\", ";
if (indexOfFirstOpeningBrace >= 0) {
jsonLeaderboardAsString.insert(indexOfFirstOpeningBrace+1, requestTimePointAsJson);
}
resp.getWriter().write(jsonLeaderboardAsString.toString());
if (indexOfFirstOpeningBrace >= 0) {
jsonLeaderboardAsString.delete(indexOfFirstOpeningBrace+1, indexOfFirstOpeningBrace+1+requestTimePointAsJson.length());
}
}
} catch (NoWindException e) {
resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e.getMessage());
}
@@ -208,9 +226,9 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
}
}
private JSONObject getLeaderboardJsonFromCacheOrCompute(Leaderboard leaderboard,
private StringBuffer getLeaderboardJsonFromCacheOrCompute(Leaderboard leaderboard,
Pair<TimePoint, ResultStates> timePointAndResultState, final TimePoint requestTimePoint) throws NoWindException {
Map<Pair<TimePoint, ResultStates>, JSONObject> cacheEntry = cache.get(leaderboard, /* waitForLatest */ false);
Map<Pair<TimePoint, ResultStates>, StringBuffer> cacheEntry = cache.get(leaderboard, /* waitForLatest */ false);
if (cacheEntry == null || !cacheEntry.containsKey(timePointAndResultState)) {
cacheMisses++;
LinkedHashSet<Pair<TimePoint, ResultStates>> timePointsAndResultStates = new LinkedHashSet<>();
@@ -218,8 +236,8 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
cache.triggerUpdate(leaderboard, new LeaderboardJsonCacheUpdateInterval(timePointsAndResultStates));
// now wait for this entry to be computed
cacheEntry = cache.get(leaderboard, /* waitForLatest */ true);
JSONObject jsonObject = cacheEntry.get(timePointAndResultState);
return jsonObject;
StringBuffer jsonObjectAsString = cacheEntry.get(timePointAndResultState);
return jsonObjectAsString;
} else {
cacheHits++;
}
@@ -432,7 +450,8 @@ public class LeaderboardJsonGetServlet extends AbstractJsonHttpServlet implement
*/
@Override
public void invalidate(Leaderboard leaderboard) {
final LinkedHashMap<Pair<TimePoint, ResultStates>, JSONObject> currentCachedValueForLeaderboard = cache.get(leaderboard, /* waitForLatest */ false);
final LinkedHashMap<Pair<TimePoint, ResultStates>, StringBuffer> currentCachedValueForLeaderboard =
cache.get(leaderboard, /* waitForLatest */ false);
cache.triggerUpdate(leaderboard, new LeaderboardJsonCacheUpdateInterval(currentCachedValueForLeaderboard.keySet()));
}
}