1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "net/disk_cache/trace.h"
6
7 #include <stdio.h>
8 #if defined(OS_WIN)
9 #include <windows.h>
10 #endif
11
12 #include "base/logging.h"
13
14 // Change this value to 1 to enable tracing on a release build. By default,
15 // tracing is enabled only on debug builds.
16 #define ENABLE_TRACING 0
17
18 #ifndef NDEBUG
19 #undef ENABLE_TRACING
20 #define ENABLE_TRACING 1
21 #endif
22
23 namespace {
24
25 const int kEntrySize = 48;
26 const int kNumberOfEntries = 5000; // 240 KB.
27
28 struct TraceBuffer {
29 int num_traces;
30 int current;
31 char buffer[kNumberOfEntries][kEntrySize];
32 };
33
34 #if ENABLE_TRACING
DebugOutput(const char * msg)35 void DebugOutput(const char* msg) {
36 #if defined(OS_WIN)
37 OutputDebugStringA(msg);
38 #else
39 NOTIMPLEMENTED();
40 #endif
41 }
42 #endif // ENABLE_TRACING
43
44 } // namespace
45
46 namespace disk_cache {
47
48 // s_trace_buffer and s_trace_object are not singletons because I want the
49 // buffer to be destroyed and re-created when the last user goes away, and it
50 // must be straightforward to access the buffer from the debugger.
51 static TraceObject* s_trace_object = NULL;
52
53 // Static.
GetTraceObject()54 TraceObject* TraceObject::GetTraceObject() {
55 if (s_trace_object)
56 return s_trace_object;
57
58 s_trace_object = new TraceObject();
59 return s_trace_object;
60 }
61
TraceObject()62 TraceObject::TraceObject() {
63 InitTrace();
64 }
65
~TraceObject()66 TraceObject::~TraceObject() {
67 DestroyTrace();
68 }
69
70 #if ENABLE_TRACING
71
72 static TraceBuffer* s_trace_buffer = NULL;
73
InitTrace(void)74 void InitTrace(void) {
75 if (s_trace_buffer)
76 return;
77
78 s_trace_buffer = new TraceBuffer;
79 memset(s_trace_buffer, 0, sizeof(*s_trace_buffer));
80 }
81
DestroyTrace(void)82 void DestroyTrace(void) {
83 delete s_trace_buffer;
84 s_trace_buffer = NULL;
85 s_trace_object = NULL;
86 }
87
Trace(const char * format,...)88 void Trace(const char* format, ...) {
89 if (!s_trace_buffer)
90 return;
91
92 va_list ap;
93 va_start(ap, format);
94
95 #if defined(OS_WIN)
96 vsprintf_s(s_trace_buffer->buffer[s_trace_buffer->current], format, ap);
97 #else
98 vsnprintf(s_trace_buffer->buffer[s_trace_buffer->current],
99 sizeof(s_trace_buffer->buffer[s_trace_buffer->current]), format,
100 ap);
101 #endif
102 s_trace_buffer->num_traces++;
103 s_trace_buffer->current++;
104 if (s_trace_buffer->current == kNumberOfEntries)
105 s_trace_buffer->current = 0;
106
107 va_end(ap);
108 }
109
110 // Writes the last num_traces to the debugger output.
DumpTrace(int num_traces)111 void DumpTrace(int num_traces) {
112 DCHECK(s_trace_buffer);
113 DebugOutput("Last traces:\n");
114
115 if (num_traces > kNumberOfEntries || num_traces < 0)
116 num_traces = kNumberOfEntries;
117
118 if (s_trace_buffer->num_traces) {
119 char line[kEntrySize + 2];
120
121 int current = s_trace_buffer->current - num_traces;
122 if (current < 0)
123 current += kNumberOfEntries;
124
125 for (int i = 0; i < num_traces; i++) {
126 memcpy(line, s_trace_buffer->buffer[current], kEntrySize);
127 line[kEntrySize] = '\0';
128 size_t length = strlen(line);
129 if (length) {
130 line[length] = '\n';
131 line[length + 1] = '\0';
132 DebugOutput(line);
133 }
134
135 current++;
136 if (current == kNumberOfEntries)
137 current = 0;
138 }
139 }
140
141 DebugOutput("End of Traces\n");
142 }
143
144 #else // ENABLE_TRACING
145
InitTrace(void)146 void InitTrace(void) {
147 return;
148 }
149
DestroyTrace(void)150 void DestroyTrace(void) {
151 s_trace_object = NULL;
152 }
153
Trace(const char * format,...)154 void Trace(const char* format, ...) {
155 }
156
157 #endif // ENABLE_TRACING
158
159 } // namespace disk_cache
160