/*

 * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package com.sun.tools.sjavac;

import java.io.File;

import java.net.URI;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Random;

import java.util.Set;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import com.sun.tools.javac.main.Main.Result;

import com.sun.tools.sjavac.comp.CompilationService;

import com.sun.tools.sjavac.options.Options;

import com.sun.tools.sjavac.pubapi.PubApi;

import com.sun.tools.sjavac.server.CompilationSubResult;

import com.sun.tools.sjavac.server.SysInfo;

/**

 * This transform compiles a set of packages containing Java sources.

 * The compile request is divided into separate sets of source files.

 * For each set a separate request thread is dispatched to a javac server

 * and the meta data is accumulated. The number of sets correspond more or

 * less to the number of cores. Less so now, than it will in the future.

 *

 * <p><b>This is NOT part of any supported API.

 * If you write code that depends on this, you do so at your own

 * risk.  This code and its internal interfaces are subject to change

 * or deletion without notice.</b></p>

 */

public class CompileJavaPackages implements Transformer {

    // The current limited sharing of data between concurrent JavaCompilers

    // in the server will not give speedups above 3 cores. Thus this limit.

    // We hope to improve this in the future.

    final static int limitOnConcurrency = 3;

    Options args;

    public void setExtra(String e) {

    }

    public void setExtra(Options a) {

        args = a;

    }

    public boolean transform(final CompilationService sjavac,

                             Map<String,Set<URI>> pkgSrcs,

                             final Set<URI>             visibleSources,

                             Map<String,Set<String>> oldPackageDependents,

                             URI destRoot,

                             final Map<String,Set<URI>>    packageArtifacts,

                             final Map<String,Map<String, Set<String>>> packageDependencies,

                             final Map<String,Map<String, Set<String>>> packageCpDependencies,

                             final Map<String, PubApi> packagePubapis,

                             final Map<String, PubApi> dependencyPubapis,

                             int debugLevel,

                             boolean incremental,

                             int numCores) {

        Log.debug("Performing CompileJavaPackages transform...");

        boolean rc = true;

        boolean concurrentCompiles = true;

        // Fetch the id.

        final String id = String.valueOf(new Random().nextInt());

        // Only keep portfile and sjavac settings..

        //String psServerSettings = Util.cleanSubOptions(Util.set("portfile","sjavac","background","keepalive"), sjavac.serverSettings());

        SysInfo sysinfo = sjavac.getSysInfo();

        int numMBytes = (int)(sysinfo.maxMemory / ((long)(1024*1024)));

        Log.debug("Server reports "+numMBytes+"MiB of memory and "+sysinfo.numCores+" cores");

        if (numCores <= 0) {

            // Set the requested number of cores to the number of cores on the server.

            numCores = sysinfo.numCores;

            Log.debug("Number of jobs not explicitly set, defaulting to "+sysinfo.numCores);

        } else if (sysinfo.numCores < numCores) {

            // Set the requested number of cores to the number of cores on the server.

            Log.debug("Limiting jobs from explicitly set "+numCores+" to cores available on server: "+sysinfo.numCores);

            numCores = sysinfo.numCores;

        } else {

            Log.debug("Number of jobs explicitly set to "+numCores);

        }

        // More than three concurrent cores does not currently give a speedup, at least for compiling the jdk

        // in the OpenJDK. This will change in the future.

        int numCompiles = numCores;

        if (numCores > limitOnConcurrency) numCompiles = limitOnConcurrency;

        // Split the work up in chunks to compiled.

        int numSources = 0;

        for (String s : pkgSrcs.keySet()) {

            Set<URI> ss = pkgSrcs.get(s);

            numSources += ss.size();

        }

        int sourcesPerCompile = numSources / numCompiles;

        // For 64 bit Java, it seems we can compile the OpenJDK 8800 files with a 1500M of heap

        // in a single chunk, with reasonable performance.

        // For 32 bit java, it seems we need 1G of heap.

        // Number experimentally determined when compiling the OpenJDK.

        // Includes space for reasonably efficient garbage collection etc,

        // Calculating backwards gives us a requirement of

        // 1500M/8800 = 175 KiB for 64 bit platforms

        // and 1G/8800 = 119 KiB for 32 bit platform

        // for each compile.....

        int kbPerFile = 175;

        String osarch = System.getProperty("os.arch");

        String dataModel = System.getProperty("sun.arch.data.model");

        if ("32".equals(dataModel)) {

            // For 32 bit platforms, assume it is slightly smaller

            // because of smaller object headers and pointers.

            kbPerFile = 119;

        }

        int numRequiredMBytes = (kbPerFile*numSources)/1024;

        Log.debug("For os.arch "+osarch+" the empirically determined heap required per file is "+kbPerFile+"KiB");

        Log.debug("Server has "+numMBytes+"MiB of heap.");

        Log.debug("Heuristics say that we need "+numRequiredMBytes+"MiB of heap for all source files.");

        // Perform heuristics to see how many cores we can use,

        // or if we have to the work serially in smaller chunks.

        if (numMBytes < numRequiredMBytes) {

            // Ouch, cannot fit even a single compile into the heap.

            // Split it up into several serial chunks.

            concurrentCompiles = false;

            // Limit the number of sources for each compile to 500.

            if (numSources < 500) {

                numCompiles = 1;

                sourcesPerCompile = numSources;

                Log.debug("Compiling as a single source code chunk to stay within heap size limitations!");

            } else if (sourcesPerCompile > 500) {

                // This number is very low, and tuned to dealing with the OpenJDK

                // where the source is >very< circular! In normal application,

                // with less circularity the number could perhaps be increased.

                numCompiles = numSources / 500;

                sourcesPerCompile = numSources/numCompiles;

                Log.debug("Compiling source as "+numCompiles+" code chunks serially to stay within heap size limitations!");

            }

        } else {

            if (numCompiles > 1) {

                // Ok, we can fit at least one full compilation on the heap.

                float usagePerCompile = (float)numRequiredMBytes / ((float)numCompiles * (float)0.7);

                int usage = (int)(usagePerCompile * (float)numCompiles);

                Log.debug("Heuristics say that for "+numCompiles+" concurrent compiles we need "+usage+"MiB");

                if (usage > numMBytes) {

                    // Ouch it does not fit. Reduce to a single chunk.

                    numCompiles = 1;

                    sourcesPerCompile = numSources;

                    // What if the relationship betweem number of compile_chunks and num_required_mbytes

                    // is not linear? Then perhaps 2 chunks would fit where 3 does not. Well, this is

                    // something to experiment upon in the future.

                    Log.debug("Limiting compile to a single thread to stay within heap size limitations!");

                }

            }

        }

        Log.debug("Compiling sources in "+numCompiles+" chunk(s)");

        // Create the chunks to be compiled.

        final CompileChunk[] compileChunks = createCompileChunks(pkgSrcs, oldPackageDependents,

                numCompiles, sourcesPerCompile);

        if (Log.isDebugging()) {

            int cn = 1;

            for (CompileChunk cc : compileChunks) {

                Log.debug("Chunk "+cn+" for "+id+" ---------------");

                cn++;

                for (URI u : cc.srcs) {

                    Log.debug(""+u);

                }

            }

        }

        long start = System.currentTimeMillis();

        // Prepare compilation calls

        List<Callable<CompilationSubResult>> compilationCalls = new ArrayList<>();

        final Object lock = new Object();

        for (int i = 0; i < numCompiles; i++) {

            CompileChunk cc = compileChunks[i];

            if (cc.srcs.isEmpty()) {

                continue;

            }

            String chunkId = id + "-" + String.valueOf(i);

            Log log = Log.get();

            compilationCalls.add(() -> {

                Log.setLogForCurrentThread(log);

                CompilationSubResult result = sjavac.compile("n/a",

                                                             chunkId,

                                                             args.prepJavacArgs(),

                                                             cc.srcs,

                                                             visibleSources);

                synchronized (lock) {

                    Util.getLines(result.stdout).forEach(Log::info);

                    Util.getLines(result.stderr).forEach(Log::error);

                }

                return result;

            });

        }

        // Perform compilations and collect results

        List<CompilationSubResult> subResults = new ArrayList<>();

        List<Future<CompilationSubResult>> futs = new ArrayList<>();

        ExecutorService exec = Executors.newFixedThreadPool(concurrentCompiles ? compilationCalls.size() : 1);

        for (Callable<CompilationSubResult> compilationCall : compilationCalls) {

            futs.add(exec.submit(compilationCall));

        }

        for (Future<CompilationSubResult> fut : futs) {

            try {

                subResults.add(fut.get());

            } catch (ExecutionException ee) {

                Log.error("Compilation failed: " + ee.getMessage());

                Log.error(ee);

            } catch (InterruptedException ie) {

                Log.error("Compilation interrupted: " + ie.getMessage());

                Log.error(ie);

                Thread.currentThread().interrupt();

            }

        }

        exec.shutdownNow();

        // Process each sub result

        for (CompilationSubResult subResult : subResults) {

            for (String pkg : subResult.packageArtifacts.keySet()) {

                Set<URI> pkgArtifacts = subResult.packageArtifacts.get(pkg);

                packageArtifacts.merge(pkg, pkgArtifacts, Util::union);

            }

            for (String pkg : subResult.packageDependencies.keySet()) {

                packageDependencies.putIfAbsent(pkg, new HashMap<>());

                packageDependencies.get(pkg).putAll(subResult.packageDependencies.get(pkg));

            }

            for (String pkg : subResult.packageCpDependencies.keySet()) {

                packageCpDependencies.putIfAbsent(pkg, new HashMap<>());

                packageCpDependencies.get(pkg).putAll(subResult.packageCpDependencies.get(pkg));

            }

            for (String pkg : subResult.packagePubapis.keySet()) {

                packagePubapis.merge(pkg, subResult.packagePubapis.get(pkg), PubApi::mergeTypes);

            }

            for (String pkg : subResult.dependencyPubapis.keySet()) {

                dependencyPubapis.merge(pkg, subResult.dependencyPubapis.get(pkg), PubApi::mergeTypes);

            }

            // Check the return values.

            if (subResult.result != Result.OK) {

                rc = false;

            }

        }

        long duration = System.currentTimeMillis() - start;

        long minutes = duration/60000;

        long seconds = (duration-minutes*60000)/1000;

        Log.debug("Compilation of "+numSources+" source files took "+minutes+"m "+seconds+"s");

        return rc;

    }

    /**

     * Split up the sources into compile chunks. If old package dependents information

     * is available, sort the order of the chunks into the most dependent first!

     * (Typically that chunk contains the java.lang package.) In the future

     * we could perhaps improve the heuristics to put the sources into even more sensible chunks.

     * Now the package are simple sorted in alphabetical order and chunked, then the chunks

     * are sorted on how dependent they are.

     *

     * @param pkgSrcs The sources to compile.

     * @param oldPackageDependents Old package dependents, if non-empty, used to sort the chunks.

     * @param numCompiles The number of chunks.

     * @param sourcesPerCompile The number of sources per chunk.

     * @return

     */

    CompileChunk[] createCompileChunks(Map<String,Set<URI>> pkgSrcs,

                                       Map<String,Set<String>> oldPackageDependents,

                                       int numCompiles,

                                       int sourcesPerCompile) {

        CompileChunk[] compileChunks = new CompileChunk[numCompiles];

        for (int i=0; i<compileChunks.length; ++i) {

            compileChunks[i] = new CompileChunk();

        }

        // Now go through the packages and spread out the source on the different chunks.

        int ci = 0;

        // Sort the packages

        String[] packageNames = pkgSrcs.keySet().toArray(new String[0]);

        Arrays.sort(packageNames);

        String from = null;

        for (String pkgName : packageNames) {

            CompileChunk cc = compileChunks[ci];

            Set<URI> s = pkgSrcs.get(pkgName);

            if (cc.srcs.size()+s.size() > sourcesPerCompile && ci < numCompiles-1) {

                from = null;

                ci++;

                cc = compileChunks[ci];

            }

            cc.numPackages++;

            cc.srcs.addAll(s);

            // Calculate nice package names to use as information when compiling.

            String justPkgName = Util.justPackageName(pkgName);

            // Fetch how many packages depend on this package from the old build state.

            Set<String> ss = oldPackageDependents.get(pkgName);

            if (ss != null) {

                // Accumulate this information onto this chunk.

                cc.numDependents += ss.size();

            }

            if (from == null || from.trim().equals("")) from = justPkgName;

            cc.pkgNames.append(justPkgName+"("+s.size()+") ");

            cc.pkgFromTos = from+" to "+justPkgName;

        }

        // If we are compiling serially, sort the chunks, so that the chunk (with the most dependents) (usually the chunk

        // containing java.lang.Object, is to be compiled first!

        // For concurrent compilation, this does not matter.

        Arrays.sort(compileChunks);

        return compileChunks;

    }

}