Speed up quoting of JSON strings by allocating a string that is big enough
and then trimming it when the length is known. This way we only have to traverse the input once. Review URL: http://codereview.chromium.org/5556012 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5951 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
erik.corry@gmail.com
parent
5423649f0a
commit
a5c8cab793
197
src/runtime.cc
197
src/runtime.cc
@ -4546,42 +4546,53 @@ static MaybeObject* Runtime_URIUnescape(Arguments args) {
|
||||
|
||||
static const unsigned int kQuoteTableLength = 128u;
|
||||
|
||||
static const char* const JsonQuotes[kQuoteTableLength] = {
|
||||
"\\u0000", "\\u0001", "\\u0002", "\\u0003",
|
||||
"\\u0004", "\\u0005", "\\u0006", "\\u0007",
|
||||
"\\b", "\\t", "\\n", "\\u000b",
|
||||
"\\f", "\\r", "\\u000e", "\\u000f",
|
||||
"\\u0010", "\\u0011", "\\u0012", "\\u0013",
|
||||
"\\u0014", "\\u0015", "\\u0016", "\\u0017",
|
||||
"\\u0018", "\\u0019", "\\u001a", "\\u001b",
|
||||
"\\u001c", "\\u001d", "\\u001e", "\\u001f",
|
||||
NULL, NULL, "\\\"", NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
"\\\\", NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
NULL, NULL, NULL, NULL,
|
||||
};
|
||||
static const int kJsonQuotesCharactersPerEntry = 8;
|
||||
static const char* const JsonQuotes =
|
||||
"\\u0000 \\u0001 \\u0002 \\u0003 "
|
||||
"\\u0004 \\u0005 \\u0006 \\u0007 "
|
||||
"\\b \\t \\n \\u000b "
|
||||
"\\f \\r \\u000e \\u000f "
|
||||
"\\u0010 \\u0011 \\u0012 \\u0013 "
|
||||
"\\u0014 \\u0015 \\u0016 \\u0017 "
|
||||
"\\u0018 \\u0019 \\u001a \\u001b "
|
||||
"\\u001c \\u001d \\u001e \\u001f "
|
||||
" ! \\\" # "
|
||||
"$ % & ' "
|
||||
"( ) * + "
|
||||
", - . / "
|
||||
"0 1 2 3 "
|
||||
"4 5 6 7 "
|
||||
"8 9 : ; "
|
||||
"< = > ? "
|
||||
"@ A B C "
|
||||
"D E F G "
|
||||
"H I J K "
|
||||
"L M N O "
|
||||
"P Q R S "
|
||||
"T U V W "
|
||||
"X Y Z [ "
|
||||
"\\\\ ] ^ _ "
|
||||
"` a b c "
|
||||
"d e f g "
|
||||
"h i j k "
|
||||
"l m n o "
|
||||
"p q r s "
|
||||
"t u v w "
|
||||
"x y z { "
|
||||
"| } ~ \177 ";
|
||||
|
||||
|
||||
// For a string that is less than 32k characters it should always be
|
||||
// possible to allocate it in new space.
|
||||
static const int kMaxGuaranteedNewSpaceString = 32 * 1024;
|
||||
|
||||
|
||||
// Doing JSON quoting cannot make the string more than this many times larger.
|
||||
static const int kJsonQuoteWorstCaseBlowup = 6;
|
||||
|
||||
|
||||
// Covers the entire ASCII range (all other characters are unchanged by JSON
|
||||
// quoting).
|
||||
static const byte JsonQuoteLengths[kQuoteTableLength] = {
|
||||
6, 6, 6, 6, 6, 6, 6, 6,
|
||||
2, 2, 2, 6, 2, 2, 6, 6,
|
||||
@ -4602,18 +4613,6 @@ static const byte JsonQuoteLengths[kQuoteTableLength] = {
|
||||
};
|
||||
|
||||
|
||||
template <typename Char>
|
||||
Char* WriteString(Char* dst, const char* src_string) {
|
||||
char c;
|
||||
for (c = *src_string; c; c = *src_string) {
|
||||
*dst = c;
|
||||
dst++;
|
||||
src_string++;
|
||||
}
|
||||
return dst;
|
||||
}
|
||||
|
||||
|
||||
template <typename StringType>
|
||||
MaybeObject* AllocateRawString(int length);
|
||||
|
||||
@ -4631,58 +4630,104 @@ MaybeObject* AllocateRawString<SeqAsciiString>(int length) {
|
||||
|
||||
|
||||
template <typename Char, typename StringType>
|
||||
static MaybeObject* QuoteJsonString(Vector<const Char> characters) {
|
||||
static MaybeObject* SlowQuoteJsonString(Vector<const Char> characters) {
|
||||
int length = characters.length();
|
||||
int quoted_length = 0;
|
||||
for (int i = 0; i < length; i++) {
|
||||
unsigned int c = characters[i];
|
||||
if (sizeof(Char) > 1u) {
|
||||
quoted_length += (c >= kQuoteTableLength) ? 1 : JsonQuoteLengths[c];
|
||||
const Char* read_cursor = characters.start();
|
||||
const Char* end = read_cursor + length;
|
||||
const int kSpaceForQuotes = 2;
|
||||
int quoted_length = kSpaceForQuotes;
|
||||
while (read_cursor < end) {
|
||||
Char c = *(read_cursor++);
|
||||
if (sizeof(Char) > 1u && static_cast<unsigned>(c) >= kQuoteTableLength) {
|
||||
quoted_length++;
|
||||
} else {
|
||||
quoted_length += JsonQuoteLengths[c];
|
||||
quoted_length += JsonQuoteLengths[static_cast<unsigned>(c)];
|
||||
}
|
||||
}
|
||||
Counters::quote_json_char_count.Increment(length);
|
||||
|
||||
// Add space for quotes.
|
||||
quoted_length += 2;
|
||||
|
||||
MaybeObject* new_alloc = AllocateRawString<StringType>(quoted_length);
|
||||
Object* new_object;
|
||||
if (!new_alloc->ToObject(&new_object)) {
|
||||
Counters::quote_json_char_recount.Increment(length);
|
||||
return new_alloc;
|
||||
}
|
||||
StringType* new_string = StringType::cast(new_object);
|
||||
|
||||
Char* write_cursor = reinterpret_cast<Char*>(
|
||||
new_string->address() + SeqAsciiString::kHeaderSize);
|
||||
*(write_cursor++) = '"';
|
||||
|
||||
read_cursor = characters.start();
|
||||
while (read_cursor < end) {
|
||||
Char c = *(read_cursor++);
|
||||
if (sizeof(Char) > 1u && static_cast<unsigned>(c) >= kQuoteTableLength) {
|
||||
*(write_cursor++) = c;
|
||||
} else {
|
||||
int len = JsonQuoteLengths[static_cast<unsigned>(c)];
|
||||
const char* replacement = JsonQuotes +
|
||||
static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
|
||||
for (int i = 0; i < len; i++) {
|
||||
*write_cursor++ = *replacement++;
|
||||
}
|
||||
}
|
||||
}
|
||||
*(write_cursor++) = '"';
|
||||
return new_string;
|
||||
}
|
||||
|
||||
|
||||
template <typename Char, typename StringType>
|
||||
static MaybeObject* QuoteJsonString(Vector<const Char> characters) {
|
||||
int length = characters.length();
|
||||
Counters::quote_json_char_count.Increment(length);
|
||||
const int kSpaceForQuotes = 2;
|
||||
int worst_case_length = length * kJsonQuoteWorstCaseBlowup + kSpaceForQuotes;
|
||||
if (worst_case_length > kMaxGuaranteedNewSpaceString) {
|
||||
return SlowQuoteJsonString<Char, StringType>(characters);
|
||||
}
|
||||
|
||||
MaybeObject* new_alloc = AllocateRawString<StringType>(worst_case_length);
|
||||
Object* new_object;
|
||||
if (!new_alloc->ToObject(&new_object)) {
|
||||
return new_alloc;
|
||||
}
|
||||
StringType* new_string = StringType::cast(new_object);
|
||||
ASSERT(Heap::new_space()->Contains(new_string));
|
||||
|
||||
STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqAsciiString::kHeaderSize);
|
||||
Char* write_cursor = reinterpret_cast<Char*>(
|
||||
new_string->address() + SeqAsciiString::kHeaderSize);
|
||||
*(write_cursor++) = '"';
|
||||
|
||||
const Char* read_cursor = characters.start();
|
||||
if (quoted_length == length + 2) {
|
||||
CopyChars(write_cursor, read_cursor, length);
|
||||
write_cursor += length;
|
||||
} else {
|
||||
const Char* end = read_cursor + length;
|
||||
while (read_cursor < end) {
|
||||
Char c = *(read_cursor++);
|
||||
if (sizeof(Char) > 1u && static_cast<unsigned>(c) >= kQuoteTableLength) {
|
||||
*(write_cursor++) = c;
|
||||
} else {
|
||||
const char* replacement = JsonQuotes[static_cast<unsigned>(c)];
|
||||
if (!replacement) {
|
||||
*(write_cursor++) = c;
|
||||
} else {
|
||||
write_cursor = WriteString(write_cursor, replacement);
|
||||
const Char* end = read_cursor + length;
|
||||
while (read_cursor < end) {
|
||||
Char c = *(read_cursor++);
|
||||
if (sizeof(Char) > 1u && static_cast<unsigned>(c) >= kQuoteTableLength) {
|
||||
*(write_cursor++) = c;
|
||||
} else {
|
||||
int len = JsonQuoteLengths[static_cast<unsigned>(c)];
|
||||
const char* replacement = JsonQuotes +
|
||||
static_cast<unsigned>(c) * kJsonQuotesCharactersPerEntry;
|
||||
write_cursor[0] = replacement[0];
|
||||
if (len > 1) {
|
||||
write_cursor[1] = replacement[1];
|
||||
if (len > 2) {
|
||||
ASSERT(len == 6);
|
||||
write_cursor[2] = replacement[2];
|
||||
write_cursor[3] = replacement[3];
|
||||
write_cursor[4] = replacement[4];
|
||||
write_cursor[5] = replacement[5];
|
||||
}
|
||||
}
|
||||
write_cursor += len;
|
||||
}
|
||||
}
|
||||
*(write_cursor++) = '"';
|
||||
ASSERT_EQ(SeqAsciiString::kHeaderSize + quoted_length * sizeof(Char),
|
||||
reinterpret_cast<Address>(write_cursor) - new_string->address());
|
||||
|
||||
int final_length =
|
||||
write_cursor - reinterpret_cast<Char*>(
|
||||
new_string->address() + SeqAsciiString::kHeaderSize);
|
||||
Heap::new_space()->ShrinkStringAtAllocationBoundary<StringType>(new_string,
|
||||
final_length);
|
||||
return new_string;
|
||||
}
|
||||
|
||||
|
||||
@ -481,7 +481,7 @@ void LargeObjectChunk::Free(Executability executable) {
|
||||
}
|
||||
|
||||
// -----------------------------------------------------------------------------
|
||||
// LargeObjectSpace
|
||||
// NewSpace
|
||||
|
||||
MaybeObject* NewSpace::AllocateRawInternal(int size_in_bytes,
|
||||
AllocationInfo* alloc_info) {
|
||||
@ -501,6 +501,18 @@ MaybeObject* NewSpace::AllocateRawInternal(int size_in_bytes,
|
||||
}
|
||||
|
||||
|
||||
template <typename StringType>
|
||||
void NewSpace::ShrinkStringAtAllocationBoundary(String* string, int length) {
|
||||
ASSERT(length <= string->length());
|
||||
ASSERT(string->IsSeqString());
|
||||
ASSERT(string->address() + StringType::SizeFor(string->length()) ==
|
||||
allocation_info_.top);
|
||||
allocation_info_.top =
|
||||
string->address() + StringType::SizeFor(length);
|
||||
string->set_length(length);
|
||||
}
|
||||
|
||||
|
||||
bool FreeListNode::IsFreeListNode(HeapObject* object) {
|
||||
return object->map() == Heap::raw_unchecked_byte_array_map()
|
||||
|| object->map() == Heap::raw_unchecked_one_pointer_filler_map()
|
||||
|
||||
@ -1643,6 +1643,11 @@ class NewSpace : public Space {
|
||||
|
||||
virtual bool ReserveSpace(int bytes);
|
||||
|
||||
// Resizes a sequential string which must be the most recent thing that was
|
||||
// allocated in new space.
|
||||
template <typename StringType>
|
||||
inline void ShrinkStringAtAllocationBoundary(String* string, int len);
|
||||
|
||||
#ifdef ENABLE_HEAP_PROTECTION
|
||||
// Protect/unprotect the space by marking it read-only/writable.
|
||||
virtual void Protect();
|
||||
|
||||
Loading…
Reference in New Issue
Block a user