1 /*
   2  * Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package org.openjdk.jigsaw;
  27 
  28 import java.security.AccessController;
  29 import java.security.PrivilegedAction;
  30 import java.util.List;
  31 import java.util.ArrayList;
  32 
  33 class Trace {
  34 
  35     static int traceLevel = 0;
  36     static boolean tracing = false;
  37 
  38     static {
  39         PrivilegedAction<String> pa = new PrivilegedAction<String>() {
  40             public String run() { return System.getenv("JIGSAW_TRACE"); }};
  41         String v = AccessController.doPrivileged(pa);
  42         if (v != null) {
  43             traceLevel = Integer.parseInt(v);
  44             tracing = traceLevel > 0;
  45         }
  46     }
  47 
  48     // Trace.trace method may be called while the classes for tracing
  49     // e.g. java.util.Formatter) are being loaded.  Cache the traces
  50     // to avoid infinite loop until the very first call completes.
  51     static class Cache {
  52         static List<String> formats = new ArrayList<String>(); 
  53         static List<Object[]> traceArgs = new ArrayList<Object[]>(); 
  54         static boolean caching = false;
  55 
  56         /**
  57          * Returns true if the trace message is added to the cache.
  58          */
  59         static synchronized boolean add(String fmt, Object ... args) {
  60             if (caching && formats != null) {
  61                 formats.add(fmt);
  62                 traceArgs.add(args);
  63                 return true;
  64             }
  65             caching = true;
  66             return false;
  67         }
  68 
  69         static synchronized boolean isEmpty() {
  70             return formats == null;
  71         }
  72 
  73         static synchronized void printAndClear() {
  74             if (isEmpty())
  75                 return;
  76 
  77             for (int i=0; i < formats.size(); i++)  {
  78                 System.out.format(formats.get(i), traceArgs.get(i));
  79             }
  80             caching = false;
  81             formats = null;
  82             traceArgs = null;
  83         }
  84     }
  85 
  86     static void trace(int level, int depth, String fmt, Object ... args) {
  87         if (level >= traceLevel)
  88             return;
  89 
  90         StringBuilder sb = new StringBuilder();
  91         sb.append("| ");
  92         for (int i = 0; i < level; i++)
  93             sb.append("  ");
  94         if (depth > 0) {
  95             for (int i = 0; i < depth; i++)
  96                 sb.append("-");
  97             sb.append(" ");
  98         }
  99         sb.append(fmt);
 100         sb.append("%n");
 101        
 102         // Cache the traces until the first call to the format method
 103         // returns to avoid recursion while classes are being loaded
 104         if (Cache.add(sb.toString(), args)) {
 105             return;
 106         }
 107 
 108         System.out.format(sb.toString(), args);
 109 
 110         if (!Cache.isEmpty()) {
 111             // now classes needed by tracing are loaded and initialized
 112             // print all cached traces
 113             Cache.printAndClear();
 114         }
 115     }
 116 
 117     static void trace(int level, String fmt, Object ... args) {
 118         trace(level, 0, fmt, args);
 119     }
 120 
 121 }