Java tutorial
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For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package com.apigee.sdk.apm.http.impl.client.cache; import java.io.IOException; import java.util.Date; import java.util.HashSet; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.Header; import org.apache.http.HttpHost; import org.apache.http.HttpRequest; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.HttpVersion; import org.apache.http.entity.ByteArrayEntity; import org.apache.http.message.BasicHttpResponse; import com.apigee.sdk.apm.http.client.cache.HttpCacheEntry; import com.apigee.sdk.apm.http.client.cache.HttpCacheStorage; import com.apigee.sdk.apm.http.client.cache.HttpCacheUpdateCallback; import com.apigee.sdk.apm.http.client.cache.HttpCacheUpdateException; import com.apigee.sdk.apm.http.client.cache.Resource; import com.apigee.sdk.apm.http.client.cache.ResourceFactory; class BasicHttpCache implements HttpCache { private final URIExtractor uriExtractor; private final ResourceFactory resourceFactory; private final int maxObjectSizeBytes; private final CacheEntryUpdater cacheEntryUpdater; private final CachedHttpResponseGenerator responseGenerator; private final CacheInvalidator cacheInvalidator; private final HttpCacheStorage storage; private final Log log = LogFactory.getLog(getClass()); public BasicHttpCache(ResourceFactory resourceFactory, HttpCacheStorage storage, CacheConfig config) { this.resourceFactory = resourceFactory; this.uriExtractor = new URIExtractor(); this.cacheEntryUpdater = new CacheEntryUpdater(resourceFactory); this.maxObjectSizeBytes = config.getMaxObjectSizeBytes(); this.responseGenerator = new CachedHttpResponseGenerator(); this.storage = storage; this.cacheInvalidator = new CacheInvalidator(this.uriExtractor, this.storage); } public BasicHttpCache(CacheConfig config) { this(new HeapResourceFactory(), new BasicHttpCacheStorage(config), config); } public BasicHttpCache() { this(new CacheConfig()); } public void flushCacheEntriesFor(HttpHost host, HttpRequest request) throws IOException { String uri = uriExtractor.getURI(host, request); storage.removeEntry(uri); } void storeInCache(HttpHost target, HttpRequest request, HttpCacheEntry entry) throws IOException { if (entry.hasVariants()) { storeVariantEntry(target, request, entry); } else { storeNonVariantEntry(target, request, entry); } } void storeNonVariantEntry(HttpHost target, HttpRequest req, HttpCacheEntry entry) throws IOException { String uri = uriExtractor.getURI(target, req); storage.putEntry(uri, entry); } void storeVariantEntry(final HttpHost target, final HttpRequest req, final HttpCacheEntry entry) throws IOException { final String parentURI = uriExtractor.getURI(target, req); final String variantURI = uriExtractor.getVariantURI(target, req, entry); storage.putEntry(variantURI, entry); HttpCacheUpdateCallback callback = new HttpCacheUpdateCallback() { public HttpCacheEntry update(HttpCacheEntry existing) throws IOException { return doGetUpdatedParentEntry(req.getRequestLine().getUri(), existing, entry, variantURI); } }; try { storage.updateEntry(parentURI, callback); } catch (HttpCacheUpdateException e) { log.warn("Could not update key [" + parentURI + "]", e); } } boolean isIncompleteResponse(HttpResponse resp, Resource resource) { int status = resp.getStatusLine().getStatusCode(); if (status != HttpStatus.SC_OK && status != HttpStatus.SC_PARTIAL_CONTENT) { return false; } Header hdr = resp.getFirstHeader("Content-Length"); if (hdr == null) return false; int contentLength; try { contentLength = Integer.parseInt(hdr.getValue()); } catch (NumberFormatException nfe) { return false; } return (resource.length() < contentLength); } HttpResponse generateIncompleteResponseError(HttpResponse response, Resource resource) { int contentLength = Integer.parseInt(response.getFirstHeader("Content-Length").getValue()); HttpResponse error = new BasicHttpResponse(HttpVersion.HTTP_1_1, HttpStatus.SC_BAD_GATEWAY, "Bad Gateway"); error.setHeader("Content-Type", "text/plain;charset=UTF-8"); String msg = String.format( "Received incomplete response " + "with Content-Length %d but actual body length %d", contentLength, resource.length()); byte[] msgBytes = msg.getBytes(); error.setHeader("Content-Length", Integer.toString(msgBytes.length)); error.setEntity(new ByteArrayEntity(msgBytes)); return error; } HttpCacheEntry doGetUpdatedParentEntry(final String requestId, final HttpCacheEntry existing, final HttpCacheEntry entry, final String variantURI) throws IOException { HttpCacheEntry src = existing; if (src == null) { src = entry; } Set<String> variants = new HashSet<String>(src.getVariantURIs()); variants.add(variantURI); Resource resource = resourceFactory.copy(requestId, src.getResource()); return new HttpCacheEntry(src.getRequestDate(), src.getResponseDate(), src.getStatusLine(), src.getAllHeaders(), resource, variants); } public HttpCacheEntry updateCacheEntry(HttpHost target, HttpRequest request, HttpCacheEntry stale, HttpResponse originResponse, Date requestSent, Date responseReceived) throws IOException { HttpCacheEntry updatedEntry = cacheEntryUpdater.updateCacheEntry(request.getRequestLine().getUri(), stale, requestSent, responseReceived, originResponse); storeInCache(target, request, updatedEntry); return updatedEntry; } public HttpResponse cacheAndReturnResponse(HttpHost host, HttpRequest request, HttpResponse originResponse, Date requestSent, Date responseReceived) throws IOException { SizeLimitedResponseReader responseReader = getResponseReader(request, originResponse); responseReader.readResponse(); if (responseReader.isLimitReached()) { return responseReader.getReconstructedResponse(); } Resource resource = responseReader.getResource(); if (isIncompleteResponse(originResponse, resource)) { return generateIncompleteResponseError(originResponse, resource); } HttpCacheEntry entry = new HttpCacheEntry(requestSent, responseReceived, originResponse.getStatusLine(), originResponse.getAllHeaders(), resource, null); storeInCache(host, request, entry); return responseGenerator.generateResponse(entry); } SizeLimitedResponseReader getResponseReader(HttpRequest request, HttpResponse backEndResponse) { return new SizeLimitedResponseReader(resourceFactory, maxObjectSizeBytes, request, backEndResponse); } public HttpCacheEntry getCacheEntry(HttpHost host, HttpRequest request) throws IOException { HttpCacheEntry root = storage.getEntry(uriExtractor.getURI(host, request)); if (root == null) return null; if (!root.hasVariants()) return root; HttpCacheEntry variant = storage.getEntry(uriExtractor.getVariantURI(host, request, root)); return variant; } public void flushInvalidatedCacheEntriesFor(HttpHost host, HttpRequest request) throws IOException { cacheInvalidator.flushInvalidatedCacheEntries(host, request); } public Set<HttpCacheEntry> getVariantCacheEntries(HttpHost host, HttpRequest request) throws IOException { Set<HttpCacheEntry> variants = new HashSet<HttpCacheEntry>(); HttpCacheEntry root = storage.getEntry(uriExtractor.getURI(host, request)); if (root != null) { if (root.hasVariants()) { for (String variantUri : root.getVariantURIs()) { variants.add(storage.getEntry(variantUri)); } } } return variants; } }