/*

 * Copyright (c) 2012, 2014, 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.PrintStream;

import java.net.URI;

import java.util.Arrays;

import java.util.Random;

import java.util.Set;

import java.util.Map;

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

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;

    }

                             Map<String,Set<String>> oldPackageDependents,

                             URI destRoot,

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

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

                             final Map<String,String>      packagePubapis,

                             int debugLevel,

                             boolean incremental,

                             int numCores,

    {

        boolean rc = true;

        boolean concurrentCompiles = true;

        // Fetch the id.

            // No explicit id set. Create a random id so that the requests can be

            // grouped properly in the server.

        }

        // Only keep portfile and sjavac settings..

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

        // Get maximum heap size from the server!

        if (sysinfo.numCores == -1) {

            Log.error("Could not query server for sysinfo!");

            return false;

        }

        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);

                }

            }

        }

        // The return values for each chunked compile.

        // The requets, might or might not run as a background thread.

        final Thread[] requests  = new Thread[numCompiles];

        long start = System.currentTimeMillis();

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

            final int ii = i;

            final CompileChunk cc = compileChunks[i];

            // Pass the num_cores and the id (appended with the chunk number) to the server.

                @Override

                public void run() {

                }

            };

            if (cc.srcs.size() > 0) {

                String numdeps = "";

                if (cc.numDependents > 0) numdeps = "(with "+cc.numDependents+" dependents) ";

                if (!incremental || cc.numPackages > 16) {

                    String info = "("+cc.pkgFromTos+")";

                    if (info.equals("( to )")) {

                        info = "";

                    }

                    Log.info("Compiling "+cc.srcs.size()+" files "+numdeps+"in "+cc.numPackages+" packages "+info);

                } else {

                    Log.info("Compiling "+cc.pkgNames+numdeps);

                }

                if (concurrentCompiles) {

                    requests[ii].start();

                }

                else {

                    requests[ii].run();

                    // If there was an error, then stop early when running single threaded.

                        return false;

                    }

                }

            }

        }

        if (concurrentCompiles) {

            // If there are background threads for the concurrent compiles, then join them.

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

                try { requests[i].join(); } catch (InterruptedException e) { }

            }

        }

        // Check the return values.

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

            if (compileChunks[i].srcs.size() > 0) {

                    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;

    }

}