1 /*
   2  * Copyright (c) 2015, 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 #ifndef SHARE_VM_LOGGING_LOGPREFIX_HPP
  25 #define SHARE_VM_LOGGING_LOGPREFIX_HPP
  26 
  27 #include "gc/shared/gcId.hpp"
  28 #include "logging/logTag.hpp"
  29 
  30 // Prefixes prepend each log message for a specified tagset with a given prefix.
  31 // These prefixes are written before the log message but after the log decorations.
  32 //
  33 // A prefix is defined as a function that takes a buffer (with some size) as argument.
  34 // This function will be called for each log message, and should write the prefix
  35 // to the given buffer. The function should return how many characters it wrote,
  36 // which should never exceed the given size.
  37 //
  38 // List of prefixes for specific tags and/or tagsets.
  39 // Syntax: LOG_PREFIX(<name of prefixer function>, LOG_TAGS(<chosen log tags>))
  40 // Where the prefixer function matches the following signature: size_t (*)(char*, size_t)
  41 #define LOG_PREFIX_LIST // Currently unused/empty
  42 
  43 // The empty prefix, used when there's no prefix defined.
  44 template <LogTagType T0, LogTagType T1, LogTagType T2, LogTagType T3, LogTagType T4, LogTagType GuardTag = LogTag::__NO_TAG>
  45 struct LogPrefix : public AllStatic {
  46   STATIC_ASSERT(GuardTag == LogTag::__NO_TAG);
  47   static size_t prefix(char* buf, size_t len) {
  48     return 0;
  49   }
  50 };
  51 
  52 #define LOG_PREFIX(fn, ...) \
  53 template <> struct LogPrefix<__VA_ARGS__> { \
  54   static size_t prefix(char* buf, size_t len) { \
  55     DEBUG_ONLY(buf[0] = '\0';) \
  56     size_t ret = fn(buf, len); \
  57     assert(ret == strlen(buf), "Length mismatch ret (" SIZE_FORMAT ") != buf length (" SIZE_FORMAT ")", ret, strlen(buf)); \
  58     return ret; \
  59   } \
  60 };
  61 LOG_PREFIX_LIST
  62 #undef LOG_PREFIX
  63 
  64 #endif // SHARE_VM_LOGGING_LOGPREFIX_HPP