com.google.gerrit.server.rules.RulesCache Maven / Gradle / Ivy
// Copyright (C) 2011 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.gerrit.server.rules;
import static com.googlecode.prolog_cafe.lang.PrologMachineCopy.save;
import com.google.common.base.Joiner;
import com.google.common.cache.Cache;
import com.google.common.collect.ImmutableList;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.server.cache.CacheModule;
import com.google.gerrit.server.config.GerritServerConfig;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.plugincontext.PluginSetContext;
import com.google.gerrit.server.project.ProjectCacheImpl;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import com.google.inject.name.Named;
import com.googlecode.prolog_cafe.exceptions.CompileException;
import com.googlecode.prolog_cafe.exceptions.SyntaxException;
import com.googlecode.prolog_cafe.exceptions.TermException;
import com.googlecode.prolog_cafe.lang.BufferingPrologControl;
import com.googlecode.prolog_cafe.lang.JavaObjectTerm;
import com.googlecode.prolog_cafe.lang.ListTerm;
import com.googlecode.prolog_cafe.lang.Prolog;
import com.googlecode.prolog_cafe.lang.PrologClassLoader;
import com.googlecode.prolog_cafe.lang.PrologMachineCopy;
import com.googlecode.prolog_cafe.lang.StructureTerm;
import com.googlecode.prolog_cafe.lang.SymbolTerm;
import com.googlecode.prolog_cafe.lang.Term;
import java.io.IOException;
import java.io.PushbackReader;
import java.io.Reader;
import java.io.StringReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.List;
import java.util.concurrent.ExecutionException;
import org.eclipse.jgit.errors.LargeObjectException;
import org.eclipse.jgit.lib.Config;
import org.eclipse.jgit.lib.Constants;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.util.RawParseUtils;
/**
* Manages a cache of compiled Prolog rules.
*
* Rules are loaded from the {@code site_path/cache/rules/rules-SHA1.jar}, where {@code SHA1} is
* the SHA1 of the Prolog {@code rules.pl} in a project's {@link RefNames#REFS_CONFIG} branch.
*/
@Singleton
public class RulesCache {
public static class Module extends CacheModule {
@Override
protected void configure() {
cache(RulesCache.CACHE_NAME, ObjectId.class, PrologMachineCopy.class)
// This cache is auxiliary to the project cache, so size it the same.
.configKey(ProjectCacheImpl.CACHE_NAME);
}
}
private static final ImmutableList PACKAGE_LIST =
ImmutableList.of(Prolog.BUILTIN, "gerrit");
static final String CACHE_NAME = "prolog_rules";
private final boolean enableProjectRules;
private final int maxDbSize;
private final int maxSrcBytes;
private final Path cacheDir;
private final Path rulesDir;
private final GitRepositoryManager gitMgr;
private final PluginSetContext predicateProviders;
private final ClassLoader systemLoader;
private final PrologMachineCopy defaultMachine;
private final Cache machineCache;
@Inject
protected RulesCache(
@GerritServerConfig Config config,
SitePaths site,
GitRepositoryManager gm,
PluginSetContext predicateProviders,
@Named(CACHE_NAME) Cache machineCache) {
maxDbSize = config.getInt("rules", null, "maxPrologDatabaseSize", 256);
maxSrcBytes = config.getInt("rules", null, "maxSourceBytes", 128 << 10);
enableProjectRules = config.getBoolean("rules", null, "enable", true) && maxSrcBytes > 0;
cacheDir = site.resolve(config.getString("cache", null, "directory"));
rulesDir = cacheDir != null ? cacheDir.resolve("rules") : null;
gitMgr = gm;
this.predicateProviders = predicateProviders;
this.machineCache = machineCache;
systemLoader = getClass().getClassLoader();
defaultMachine = save(newEmptyMachine(systemLoader));
}
public boolean isProjectRulesEnabled() {
return enableProjectRules;
}
/**
* Locate a cached Prolog machine state, or create one if not available.
*
* @return a Prolog machine, after loading the specified rules.
* @throws CompileException the machine cannot be created.
*/
public synchronized PrologMachineCopy loadMachine(Project.NameKey project, ObjectId rulesId)
throws CompileException {
if (!enableProjectRules || project == null || rulesId == null) {
return defaultMachine;
}
try {
return machineCache.get(rulesId, () -> createMachine(project, rulesId));
} catch (ExecutionException e) {
if (e.getCause() instanceof CompileException) {
throw new CompileException(e.getCause().getMessage(), e);
}
throw new CompileException("Error while consulting rules from " + project, e);
}
}
public PrologMachineCopy loadMachine(String name, Reader in) throws CompileException {
PrologMachineCopy pmc = consultRules(name, in);
if (pmc == null) {
throw new CompileException("Cannot consult rules from the stream " + name);
}
return pmc;
}
private PrologMachineCopy createMachine(Project.NameKey project, ObjectId rulesId)
throws CompileException {
// If the rules are available as a complied JAR on local disk, prefer
// that over dynamic consult as the bytecode will be faster.
//
if (rulesDir != null) {
Path jarPath = rulesDir.resolve("rules-" + rulesId.getName() + ".jar");
if (Files.isRegularFile(jarPath)) {
URL[] cp = new URL[] {toURL(jarPath)};
return save(newEmptyMachine(URLClassLoader.newInstance(cp, systemLoader)));
}
}
// Dynamically consult the rules into the machine's internal database.
//
String rules = read(project, rulesId);
PrologMachineCopy pmc = consultRules("rules.pl", new StringReader(rules));
if (pmc == null) {
throw new CompileException("Cannot consult rules of " + project);
}
return pmc;
}
private PrologMachineCopy consultRules(String name, Reader rules) throws CompileException {
BufferingPrologControl ctl = newEmptyMachine(systemLoader);
PushbackReader in = new PushbackReader(rules, Prolog.PUSHBACK_SIZE);
try {
if (!ctl.execute(
Prolog.BUILTIN, "consult_stream", SymbolTerm.intern(name), new JavaObjectTerm(in))) {
return null;
}
} catch (SyntaxException e) {
throw new CompileException(e.toString(), e);
} catch (TermException e) {
Term m = e.getMessageTerm();
if (m instanceof StructureTerm && "syntax_error".equals(m.name()) && m.arity() >= 1) {
StringBuilder msg = new StringBuilder();
if (m.arg(0) instanceof ListTerm) {
msg.append(Joiner.on(' ').join(((ListTerm) m.arg(0)).toJava()));
} else {
msg.append(m.arg(0).toString());
}
if (m.arity() == 2 && m.arg(1) instanceof StructureTerm && "at".equals(m.arg(1).name())) {
Term at = m.arg(1).arg(0).dereference();
if (at instanceof ListTerm) {
msg.append(" at: ");
msg.append(prettyProlog(at));
}
}
throw new CompileException(msg.toString(), e);
}
throw new CompileException("Error while consulting rules from " + name, e);
} catch (RuntimeException e) {
throw new CompileException("Error while consulting rules from " + name, e);
}
return save(ctl);
}
private static String prettyProlog(Term at) {
StringBuilder b = new StringBuilder();
for (Object o : ((ListTerm) at).toJava()) {
if (o instanceof Term) {
Term t = (Term) o;
if (!(t instanceof StructureTerm)) {
b.append(t.toString()).append(' ');
continue;
}
switch (t.name()) {
case "atom":
SymbolTerm atom = (SymbolTerm) t.arg(0);
b.append(atom.toString());
break;
case "var":
b.append(t.arg(0).toString());
break;
}
} else {
b.append(o);
}
}
return b.toString().trim();
}
private String read(Project.NameKey project, ObjectId rulesId) throws CompileException {
try (Repository git = gitMgr.openRepository(project)) {
try {
ObjectLoader ldr = git.open(rulesId, Constants.OBJ_BLOB);
byte[] raw = ldr.getCachedBytes(maxSrcBytes);
return RawParseUtils.decode(raw);
} catch (LargeObjectException e) {
throw new CompileException("rules of " + project + " are too large", e);
} catch (RuntimeException | IOException e) {
throw new CompileException("Cannot load rules of " + project, e);
}
} catch (IOException e) {
throw new CompileException("Cannot open repository " + project, e);
}
}
private BufferingPrologControl newEmptyMachine(ClassLoader cl) {
BufferingPrologControl ctl = new BufferingPrologControl();
ctl.setMaxDatabaseSize(maxDbSize);
ctl.setPrologClassLoader(
new PrologClassLoader(new PredicateClassLoader(predicateProviders, cl)));
ctl.setEnabled(EnumSet.allOf(Prolog.Feature.class), false);
List packages = new ArrayList<>();
packages.addAll(PACKAGE_LIST);
predicateProviders.runEach(
predicateProvider -> packages.addAll(predicateProvider.getPackages()));
// Bootstrap the interpreter and ensure there is clean state.
ctl.initialize(packages.toArray(new String[packages.size()]));
return ctl;
}
private static URL toURL(Path jarPath) throws CompileException {
try {
return jarPath.toUri().toURL();
} catch (MalformedURLException e) {
throw new CompileException("Cannot create URL for " + jarPath, e);
}
}
}