Line data Source code
1 : /* This Source Code Form is subject to the terms of the Mozilla Public
2 : * License, v. 2.0. If a copy of the MPL was not distributed with this
3 : * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4 :
5 : #include "ThreadAnnotation.h"
6 :
7 : #include <stddef.h>
8 :
9 : #include "mozilla/Assertions.h"
10 : #include "mozilla/StaticMutex.h"
11 : #include "mozilla/TypeTraits.h"
12 : #include "mozilla/UniquePtr.h"
13 :
14 : #include "prthread.h"
15 : #include "nsDebug.h"
16 : #include "nsExceptionHandler.h"
17 : #include "nsString.h"
18 : #include "nsTArray.h"
19 :
20 : using mozilla::StaticMutex;
21 : using mozilla::StaticMutexAutoLock;
22 : using mozilla::UniquePtr;
23 :
24 : namespace CrashReporter {
25 :
26 : namespace {
27 :
28 : // Protects access to sInitialized and sThreadAnnotations.
29 3 : static StaticMutex sMutex;
30 :
31 : class ThreadAnnotationSpan {
32 : public:
33 0 : ThreadAnnotationSpan(uint32_t aBegin, uint32_t aEnd)
34 0 : : mBegin(aBegin)
35 0 : , mEnd(aEnd)
36 : {
37 0 : MOZ_ASSERT(mBegin < mEnd);
38 0 : }
39 :
40 : ~ThreadAnnotationSpan();
41 :
42 : class Comparator {
43 : public:
44 0 : bool Equals(const ThreadAnnotationSpan* const& a,
45 : const ThreadAnnotationSpan* const& b) const
46 : {
47 0 : return a->mBegin == b->mBegin;
48 : }
49 :
50 0 : bool LessThan(const ThreadAnnotationSpan* const& a,
51 : const ThreadAnnotationSpan* const& b) const
52 : {
53 0 : return a->mBegin < b->mBegin;
54 : }
55 : };
56 :
57 : private:
58 : // ~ThreadAnnotationSpan() does nontrivial thing. Make sure we don't
59 : // instantiate accidentally.
60 : ThreadAnnotationSpan(const ThreadAnnotationSpan& aOther) = delete;
61 : ThreadAnnotationSpan& operator=(const ThreadAnnotationSpan& aOther) = delete;
62 :
63 : friend class ThreadAnnotationData;
64 : friend class Comparator;
65 :
66 : uint32_t mBegin;
67 : uint32_t mEnd;
68 : };
69 :
70 : // This class keeps the flat version of thread annotations for each thread.
71 : // When a thread calls CrashReporter::SetCurrentThreadName(), it adds
72 : // information about the calling thread (thread id and name) to this class.
73 : // When crash happens, the crash reporter gets flat representation and add to
74 : // the crash annotation file.
75 : class ThreadAnnotationData {
76 : public:
77 0 : ThreadAnnotationData()
78 0 : {}
79 :
80 0 : ~ThreadAnnotationData()
81 0 : {}
82 :
83 : // Adds <pre> tid:"thread name",</pre> annotation to the current annotations.
84 : // Returns an instance of ThreadAnnotationSpan for cleanup on thread
85 : // termination.
86 : ThreadAnnotationSpan*
87 0 : AddThreadAnnotation(ThreadId aTid, const char* aThreadName)
88 : {
89 0 : if (!aTid || !aThreadName) {
90 0 : return nullptr;
91 : }
92 :
93 0 : uint32_t oldLength = mData.Length();
94 0 : mData.AppendPrintf("%u:\"%s\",", aTid, aThreadName);
95 0 : uint32_t newLength = mData.Length();
96 :
97 0 : ThreadAnnotationSpan* rv = new ThreadAnnotationSpan(oldLength, newLength);
98 0 : mDataSpans.AppendElement(rv);
99 0 : return rv;
100 : }
101 :
102 : // Called on thread termination. Removes the thread annotation, represented as
103 : // ThreadAnnotationSpan, from the flat representation.
104 0 : void EraseThreadAnnotation(const ThreadAnnotationSpan& aThreadInfo)
105 : {
106 0 : uint32_t begin = aThreadInfo.mBegin;
107 0 : uint32_t end = aThreadInfo.mEnd;
108 :
109 0 : if (!(begin < end &&
110 0 : end <= mData.Length())) {
111 0 : return;
112 : }
113 :
114 0 : uint32_t cutLength = end - begin;
115 0 : mData.Cut(begin, cutLength);
116 :
117 : // Adjust the ThreadAnnotationSpan affected by data shifting.
118 0 : size_t index = mDataSpans.BinaryIndexOf(&aThreadInfo,
119 0 : ThreadAnnotationSpan::Comparator());
120 0 : for (size_t i = index + 1; i < mDataSpans.Length(); i++) {
121 0 : ThreadAnnotationSpan* elem = mDataSpans[i];
122 :
123 0 : MOZ_ASSERT(elem->mBegin >= cutLength);
124 0 : MOZ_ASSERT(elem->mEnd > cutLength);
125 :
126 0 : elem->mBegin -= cutLength;
127 0 : elem->mEnd -= cutLength;
128 : }
129 :
130 : // No loner tracking aThreadInfo.
131 0 : mDataSpans.RemoveElementAt(index);
132 : }
133 :
134 : // Gets the flat representation of thread annotations.
135 0 : void GetData(const std::function<void(const char*)>& aCallback)
136 : {
137 0 : aCallback(mData.BeginReading());
138 0 : }
139 : private:
140 : // The flat representation of thread annotations.
141 : nsCString mData;
142 :
143 : // This array tracks the created ThreadAnnotationSpan instances so that we
144 : // can make adjustments accordingly when we cut substrings from mData on
145 : // thread exit.
146 : nsTArray<ThreadAnnotationSpan*> mDataSpans;
147 : };
148 :
149 : template<typename T>
150 : class DeleteWithLock
151 : {
152 : public:
153 : constexpr DeleteWithLock() {}
154 :
155 : void operator()(T* aPtr) const
156 : {
157 : static_assert(sizeof(T) > 0, "T must be complete");
158 : StaticMutexAutoLock lock(sMutex);
159 :
160 : delete aPtr;
161 : }
162 : };
163 :
164 : static bool sInitialized = false;
165 3 : static UniquePtr<ThreadAnnotationData> sThreadAnnotations;
166 :
167 : static unsigned sTLSThreadInfoKey = (unsigned) -1;
168 0 : void ThreadLocalDestructor(void* aUserData)
169 : {
170 0 : MOZ_ASSERT(aUserData);
171 :
172 0 : StaticMutexAutoLock lock(sMutex);
173 :
174 : ThreadAnnotationSpan* aThreadInfo =
175 0 : static_cast<ThreadAnnotationSpan*>(aUserData);
176 0 : delete aThreadInfo;
177 0 : }
178 :
179 : // This is called on thread termination.
180 0 : ThreadAnnotationSpan::~ThreadAnnotationSpan()
181 : {
182 : // Note that we can't lock the mutex here because this function may be called
183 : // from SetCurrentThreadName().
184 0 : sMutex.AssertCurrentThreadOwns();
185 :
186 0 : if (sThreadAnnotations) {
187 0 : sThreadAnnotations->EraseThreadAnnotation(*this);
188 : }
189 0 : }
190 :
191 : } // Anonymous namespace.
192 :
193 0 : void InitThreadAnnotation()
194 : {
195 0 : StaticMutexAutoLock lock(sMutex);
196 :
197 0 : if (sInitialized) {
198 0 : return;
199 : }
200 :
201 : PRStatus status = PR_NewThreadPrivateIndex(&sTLSThreadInfoKey,
202 0 : &ThreadLocalDestructor);
203 0 : if (status == PR_FAILURE) {
204 0 : return;
205 : }
206 :
207 0 : sInitialized = true;
208 :
209 0 : sThreadAnnotations = mozilla::MakeUnique<ThreadAnnotationData>();
210 : }
211 :
212 76 : void SetCurrentThreadName(const char* aName)
213 : {
214 76 : if (PR_GetThreadPrivate(sTLSThreadInfoKey)) {
215 : // Explicitly set TLS value to null (and call the dtor function ) before
216 : // acquiring sMutex to avoid reentrant deadlock.
217 0 : PR_SetThreadPrivate(sTLSThreadInfoKey, nullptr);
218 : }
219 :
220 76 : StaticMutexAutoLock lock(sMutex);
221 :
222 76 : if (!sInitialized) {
223 76 : return;
224 : }
225 :
226 : ThreadAnnotationSpan* threadInfo =
227 0 : sThreadAnnotations->AddThreadAnnotation(CurrentThreadId(),
228 0 : aName);
229 : // This may destroy the old insatnce.
230 0 : PR_SetThreadPrivate(sTLSThreadInfoKey, threadInfo);
231 : }
232 :
233 0 : void GetFlatThreadAnnotation(const std::function<void(const char*)>& aCallback)
234 : {
235 0 : StaticMutexAutoLock lock(sMutex);
236 :
237 0 : if (sThreadAnnotations) {
238 0 : sThreadAnnotations->GetData(aCallback);
239 : } else {
240 : // Maybe already shutdown: call aCallback with empty annotation data.
241 0 : aCallback("");
242 : }
243 0 : }
244 :
245 0 : void ShutdownThreadAnnotation()
246 : {
247 0 : StaticMutexAutoLock lock(sMutex);
248 :
249 0 : sInitialized = false;
250 0 : sThreadAnnotations.reset();
251 0 : }
252 :
253 : }
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