const char*
ThreadStackHelper::AppendJSEntry(const volatile StackEntry* aEntry,
intptr_t& aAvailableBufferSize,
const char* aPrevLabel)
{
// May be called from another thread or inside a signal handler.
// We assume querying the script is safe but we must not manupulate it.
// Also we must not allocate any memory from heap.
MOZ_ASSERT(aEntry->isJs());
MOZ_ASSERT(aEntry->script());
const char* label;
if (IsChromeJSScript(aEntry->script())) {
const char* filename = JS_GetScriptFilename(aEntry->script());
const unsigned lineno = JS_PCToLineNumber(aEntry->script(), aEntry->pc());
MOZ_ASSERT(filename);
char buffer[128]; // Enough to fit longest js file name from the tree
// Some script names are in the form "foo -> bar -> baz".
// Here we find the origin of these redirected scripts.
const char* basename = GetPathAfterComponent(filename, " -> ");
if (basename) {
filename = basename;
}
basename = GetFullPathForScheme(filename, "chrome://");
if (!basename) {
basename = GetFullPathForScheme(filename, "resource://");
}
if (!basename) {
// If the (add-on) script is located under the {profile}/extensions
// directory, extract the path after the /extensions/ part.
basename = GetPathAfterComponent(filename, "/extensions/");
}
if (!basename) {
// Only keep the file base name for paths outside the above formats.
basename = strrchr(filename, '/');
basename = basename ? basename + 1 : filename;
// Look for Windows path separator as well.
filename = strrchr(basename, '\\');
if (filename) {
basename = filename + 1;
}
}
size_t len = snprintf_literal(buffer, "%s:%u", basename, lineno);
if (len < sizeof(buffer)) {
if (mStackToFill->IsSameAsEntry(aPrevLabel, buffer)) {
return aPrevLabel;
}
// Keep track of the required buffer size
aAvailableBufferSize -= (len + 1);
if (aAvailableBufferSize >= 0) {
// Buffer is big enough.
return mStackToFill->InfallibleAppendViaBuffer(buffer, len);
}
// Buffer is not big enough; fall through to using static label below.
}
// snprintf failed or buffer is not big enough.
label = "(chrome script)";
} else {
label = "(content script)";
}
if (mStackToFill->IsSameAsEntry(aPrevLabel, label)) {
return aPrevLabel;
}
mStackToFill->infallibleAppend(label);
return label;
}
void
ThreadStackHelper::CollectPseudoEntry(const js::ProfileEntry& aEntry)
{
// For non-js frames we just include the raw label.
if (!aEntry.isJs()) {
const char* entryLabel = aEntry.label();
// entryLabel is a statically allocated string, so we want to store a
// reference to it without performing any allocations. This is important, as
// we aren't allowed to allocate within this function.
//
// The variant for this kind of label in our HangStack object is a
// `nsCString`, which normally contains heap allocated string data. However,
// `nsCString` has an optimization for literal strings which causes the
// backing data to not be copied when being copied between nsCString
// objects.
//
// We take advantage of that optimization by creating a nsCString object
// which has the LITERAL flag set. Without this optimization, this code
// would be incorrect.
nsCString label;
label.AssignLiteral(entryLabel, strlen(entryLabel));
// Let's make sure we don't deadlock here, by asserting that `label`'s
// backing data matches.
MOZ_RELEASE_ASSERT(label.BeginReading() == entryLabel,
"String copy performed during ThreadStackHelper::CollectPseudoEntry");
TryAppendFrame(label);
return;
}
if (!aEntry.script()) {
TryAppendFrame(HangEntrySuppressed());
return;
}
if (!IsChromeJSScript(aEntry.script())) {
TryAppendFrame(HangEntryContent());
return;
}
// Rather than using the profiler's dynamic string, we compute our own string.
// This is because we want to do some size-saving strategies, and throw out
// information which won't help us as much.
// XXX: We currently don't collect the function name which hung.
const char* filename = JS_GetScriptFilename(aEntry.script());
unsigned lineno = JS_PCToLineNumber(aEntry.script(), aEntry.pc());
// Some script names are in the form "foo -> bar -> baz".
// Here we find the origin of these redirected scripts.
const char* basename = GetPathAfterComponent(filename, " -> ");
if (basename) {
filename = basename;
}
// Strip chrome:// or resource:// off of the filename if present.
basename = GetFullPathForScheme(filename, "chrome://");
if (!basename) {
basename = GetFullPathForScheme(filename, "resource://");
}
if (!basename) {
// If we're in an add-on script, under the {profile}/extensions
// directory, extract the path after the /extensions/ part.
basename = GetPathAfterComponent(filename, "/extensions/");
}
if (!basename) {
// Only keep the file base name for paths outside the above formats.
basename = strrchr(filename, '/');
basename = basename ? basename + 1 : filename;
// Look for Windows path separator as well.
filename = strrchr(basename, '\\');
if (filename) {
basename = filename + 1;
}
}
char buffer[128]; // Enough to fit longest js file name from the tree
size_t len = SprintfLiteral(buffer, "%s:%u", basename, lineno);
if (len < sizeof(buffer)) {
mDesiredBufferSize += len + 1;
if (mStackToFill->stack().Capacity() > mStackToFill->stack().Length() &&
(mStackToFill->strbuffer().Capacity() -
mStackToFill->strbuffer().Length()) > len + 1) {
// NOTE: We only increment this if we're going to successfully append.
mDesiredStackSize += 1;
uint32_t start = mStackToFill->strbuffer().Length();
mStackToFill->strbuffer().AppendElements(buffer, len);
mStackToFill->strbuffer().AppendElement('\0');
mStackToFill->stack().AppendElement(HangEntryBufOffset(start));
return;
}
}
TryAppendFrame(HangEntryChromeScript());
}
