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
DebugOutput(const char * msg)34 void DebugOutput(const char* msg) {
35 #if defined(OS_WIN)
36 OutputDebugStringA(msg);
37 #else
38 NOTIMPLEMENTED();
39 #endif
40 }
41
42 } // namespace
43
44 namespace disk_cache {
45
46 // s_trace_buffer and s_trace_object are not singletons because I want the
47 // buffer to be destroyed and re-created when the last user goes away, and it
48 // must be straightforward to access the buffer from the debugger.
49 static TraceObject* s_trace_object = NULL;
50
51 // Static.
GetTraceObject()52 TraceObject* TraceObject::GetTraceObject() {
53 if (s_trace_object)
54 return s_trace_object;
55
56 s_trace_object = new TraceObject();
57 return s_trace_object;
58 }
59
60 #if ENABLE_TRACING
61
62 static TraceBuffer* s_trace_buffer = NULL;
63
InitTrace(void)64 void InitTrace(void) {
65 if (s_trace_buffer)
66 return;
67
68 s_trace_buffer = new TraceBuffer;
69 memset(s_trace_buffer, 0, sizeof(*s_trace_buffer));
70 }
71
DestroyTrace(void)72 void DestroyTrace(void) {
73 DCHECK(s_trace_buffer);
74 delete s_trace_buffer;
75 s_trace_buffer = NULL;
76 s_trace_object = NULL;
77 }
78
Trace(const char * format,...)79 void Trace(const char* format, ...) {
80 DCHECK(s_trace_buffer);
81 va_list ap;
82 va_start(ap, format);
83
84 #if defined(OS_WIN)
85 vsprintf_s(s_trace_buffer->buffer[s_trace_buffer->current], format, ap);
86 #else
87 vsnprintf(s_trace_buffer->buffer[s_trace_buffer->current],
88 sizeof(s_trace_buffer->buffer[s_trace_buffer->current]), format,
89 ap);
90 #endif
91 s_trace_buffer->num_traces++;
92 s_trace_buffer->current++;
93 if (s_trace_buffer->current == kNumberOfEntries)
94 s_trace_buffer->current = 0;
95
96 va_end(ap);
97 }
98
99 // Writes the last num_traces to the debugger output.
DumpTrace(int num_traces)100 void DumpTrace(int num_traces) {
101 DCHECK(s_trace_buffer);
102 DebugOutput("Last traces:\n");
103
104 if (num_traces > kNumberOfEntries || num_traces < 0)
105 num_traces = kNumberOfEntries;
106
107 if (s_trace_buffer->num_traces) {
108 char line[kEntrySize + 2];
109
110 int current = s_trace_buffer->current - num_traces;
111 if (current < 0)
112 current += kNumberOfEntries;
113
114 for (int i = 0; i < num_traces; i++) {
115 memcpy(line, s_trace_buffer->buffer[current], kEntrySize);
116 line[kEntrySize] = '\0';
117 size_t length = strlen(line);
118 if (length) {
119 line[length] = '\n';
120 line[length + 1] = '\0';
121 DebugOutput(line);
122 }
123
124 current++;
125 if (current == kNumberOfEntries)
126 current = 0;
127 }
128 }
129
130 DebugOutput("End of Traces\n");
131 }
132
133 #else // ENABLE_TRACING
134
InitTrace(void)135 void InitTrace(void) {
136 return;
137 }
138
DestroyTrace(void)139 void DestroyTrace(void) {
140 s_trace_object = NULL;
141 }
142
Trace(const char * format,...)143 void Trace(const char* format, ...) {
144 }
145
146 #endif // ENABLE_TRACING
147
148 } // namespace disk_cache
149