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   * Copyright (c) 2012, 2019, 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 openjdk.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 openjdk.tools.javac.main.Main.Result;
  import openjdk.tools.sjavac.comp.CompilationService;
  import openjdk.tools.sjavac.options.Options;
  import openjdk.tools.sjavac.pubapi.PubApi;
  import openjdk.tools.sjavac.server.CompilationSubResult;
  import openjdk.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 between 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(),
                                                               Collections.emptyList(),
                                                               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;
      }
  }
  