Bug 1034588

Description of problem:


Assuming you configure KnowledgeAgent/ResourceChangeScanner with ChangeSet.xml to connect to Guvnor. In addition, you configure drools.resource.urlcache to enable local file cache.

The following sequence happens when ResourceChangeScanner detects package update:

(A) UrlResource.getInputStream() reads the package from Guvnor and persist it as a local file cache.
(B) UrlResource.getInputStream() returns the package from Guvnor again and return the InputStream to KnowledgeAgent.

    public InputStream getInputStream() throws IOException {
        try {
            long lastMod  = grabLastMod();
            if (lastMod == 0) {
                //we will try the cache...
                if (cacheFileExists()) return fromCache();
            }
            if (lastMod > 0 && lastMod > lastRead) {
                if (CACHE_DIR != null && url.getProtocol().equals("http") || url.getProtocol().equals("https")) {
                    //lets grab a copy and cache it in case we need it in future...
   (A)==>           cacheStream();
                    lastMod = getCacheFile().lastModified(); // added by BZ1027221
                }
            }
            this.lastRead = lastMod;
   (B)==> return grabStream();
        } catch (IOException e) {
            if (cacheFileExists()) {
                return fromCache();
            } else {
                throw e;
            }
        }
    }

If the package is updated again in Guvnor between (A) and (B), the local file cache stores the stale package version. It will be an issue when Guvnor goes down and the client reboots (= will use the local file cache).

Steps to Reproduce:

1. Use latest 5.3.x drools-core (includes BZ917787, BZ1027216, BZ1027221, BZ1034030)
2. Set a breakpoint in UrlResource.getInputStream() before "return grabStream();" in client.
3. Start Guvnor
4. Start a client
5. Update an asset and build a package in Guvnor (= pkg_ver2)
6. After stopping at the breakpoint, update an asset and build a package in Guvnor again (= pkg_ver3)
7. Resume the debugger (Now, memory = pkg_ver3 , local cache file = pkg_ver2)
8. Rules will run with pkg_ver3
9. Shutdown Guvnor
10. Reboot the client (will read the local cache file)
11. Rules will run with pkg_ver2 until it gets updated by KnowlegeAgent+Guvnor

Actual results:

The problem is the mismatch between 8 and 11.

8. Rules will run with pkg_ver3
11. Rules will run with pkg_ver2 until it gets updated by KnowlegeAgent+Guvnor

Expected results:

UrlResource.getInputStream() should not return a newer version than the local cache file. So:

8. Rules will run with pkg_ver2
11. Rules will run with pkg_ver2 until it gets updated by KnowlegeAgent+Guvnor