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chore: Introduce small buffer in redis parser #4076

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merged 2 commits into from
Jan 7, 2025
Merged

chore: Introduce small buffer in redis parser #4076

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8a52826
chore: Introduce small buffer in redis parser
romange Dec 14, 2024
6a8ec70
chore: comments fixes
romange Jan 6, 2025
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74 changes: 59 additions & 15 deletions src/facade/redis_parser.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
//
#include "facade/redis_parser.h"

#include <absl/strings/escaping.h>
#include <absl/strings/numbers.h>

#include "base/logging.h"
Expand All @@ -18,6 +19,9 @@ auto RedisParser::Parse(Buffer str, uint32_t* consumed, RespExpr::Vec* res) -> R
*consumed = 0;
res->clear();

DVLOG(2) << "Parsing: "
<< absl::CHexEscape(string_view{reinterpret_cast<const char*>(str.data()), str.size()});

if (state_ == CMD_COMPLETE_S) {
if (InitStart(str[0], res)) {
// We recognized a non-INLINE state, starting with a special char.
Expand Down Expand Up @@ -62,6 +66,18 @@ auto RedisParser::Parse(Buffer str, uint32_t* consumed, RespExpr::Vec* res) -> R
case BULK_STR_S:
resultc = ConsumeBulk(str);
break;
case SLASH_N_S:
if (str[0] != '\n') {
resultc.first = BAD_STRING;
} else {
resultc = {OK, 1};
if (arg_c_ == '_') {
cached_expr_->emplace_back(RespExpr::NIL);
cached_expr_->back().u = Buffer{};
}
HandleFinishArg();
}
break;
default:
LOG(FATAL) << "Unexpected state " << int(state_);
}
Expand All @@ -76,13 +92,16 @@ auto RedisParser::Parse(Buffer str, uint32_t* consumed, RespExpr::Vec* res) -> R
}

if (resultc.first == INPUT_PENDING) {
DCHECK(str.empty());
StashState(res);
}
return resultc.first;
}

if (resultc.first == OK) {
DCHECK(cached_expr_);
DCHECK_EQ(0, small_len_);

if (res != cached_expr_) {
DCHECK(!stash_.empty());

Expand Down Expand Up @@ -233,15 +252,27 @@ auto RedisParser::ParseLen(Buffer str, int64_t* res) -> ResultConsumed {
const char* s = reinterpret_cast<const char*>(str.data());
const char* pos = reinterpret_cast<const char*>(memchr(s, '\n', str.size()));
if (!pos) {
Result r = INPUT_PENDING;
if (str.size() >= 32) {
LOG(WARNING) << "Unexpected format " << string_view{s, str.size()};
r = BAD_ARRAYLEN;
if (str.size() + small_len_ < small_buf_.size()) {
memcpy(&small_buf_[small_len_], str.data(), str.size());
small_len_ += str.size();
return {INPUT_PENDING, str.size()};
}
return {r, 0};
LOG(WARNING) << "Unexpected format " << string_view{s, str.size()};
return ResultConsumed{BAD_ARRAYLEN, 0};
}

unsigned consumed = pos - s + 1;
if (small_len_ > 0) {
if (small_len_ + consumed >= small_buf_.size()) {
return ResultConsumed{BAD_ARRAYLEN, consumed};
}
memcpy(&small_buf_[small_len_], str.data(), consumed);
small_len_ += consumed;
s = small_buf_.data();
pos = s + small_len_ - 1;
small_len_ = 0;
}

if (pos[-1] != '\r') {
return {BAD_ARRAYLEN, consumed};
}
Expand Down Expand Up @@ -320,12 +351,6 @@ auto RedisParser::ConsumeArrayLen(Buffer str) -> ResultConsumed {
auto RedisParser::ParseArg(Buffer str) -> ResultConsumed {
DCHECK(!str.empty());

unsigned min_len = 2 + int(arg_c_ != '_');

if (str.size() < min_len) {
return {INPUT_PENDING, 0};
}

if (arg_c_ == '$') {
int64_t len;

Expand All @@ -352,12 +377,21 @@ auto RedisParser::ParseArg(Buffer str) -> ResultConsumed {
}

DCHECK(!server_mode_);

if (arg_c_ == '_') { // Resp3 NIL
// '\r','\n'
if (str[0] != '\r' || str[1] != '\n') {
// "_\r\n", with '_' consumed into arg_c_.
DCHECK_LT(small_len_, 2u); // must be because we never fill here with more than 2 bytes.
DCHECK_GE(str.size(), 1u);

if (str[0] != '\r' || (str.size() > 1 && str[1] != '\n')) {
return {BAD_STRING, 0};
}

if (str.size() == 1) {
state_ = SLASH_N_S;
return {INPUT_PENDING, 1};
}

cached_expr_->emplace_back(RespExpr::NIL);
cached_expr_->back().u = Buffer{};
HandleFinishArg();
Expand All @@ -371,6 +405,9 @@ auto RedisParser::ParseArg(Buffer str) -> ResultConsumed {
char* s = reinterpret_cast<char*>(str.data());
char* eol = reinterpret_cast<char*>(memchr(s, '\n', str.size()));

// TODO: in client mode we still may not consume everything (see INPUT_PENDING below).
// It's not a problem, because we need consume all the input only in server mode.

if (arg_c_ == '+' || arg_c_ == '-') { // Simple string or error.
DCHECK(!server_mode_);
if (!eol) {
Expand Down Expand Up @@ -421,9 +458,9 @@ auto RedisParser::ParseArg(Buffer str) -> ResultConsumed {
}

auto RedisParser::ConsumeBulk(Buffer str) -> ResultConsumed {
auto& bulk_str = get<Buffer>(cached_expr_->back().u);

DCHECK_EQ(small_len_, 0);
uint32_t consumed = 0;
auto& bulk_str = get<Buffer>(cached_expr_->back().u);

if (str.size() >= bulk_len_) {
consumed = bulk_len_;
Expand All @@ -446,6 +483,12 @@ auto RedisParser::ConsumeBulk(Buffer str) -> ResultConsumed {
}
HandleFinishArg();
return {OK, consumed + 2};
} else if (str.size() == 1) {
if (str[0] != '\r') {
return {BAD_STRING, consumed};
}
state_ = SLASH_N_S;
consumed++;
}
return {INPUT_PENDING, consumed};
}
Expand Down Expand Up @@ -490,6 +533,7 @@ void RedisParser::HandleFinishArg() {
}
cached_expr_ = parse_stack_.back().second;
}
small_len_ = 0;
}

void RedisParser::ExtendLastString(Buffer str) {
Expand Down
6 changes: 4 additions & 2 deletions src/facade/redis_parser.h
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Original file line number Diff line number Diff line change
Expand Up @@ -45,8 +45,6 @@ class RedisParser {
* part of str because parser caches the intermediate state internally according to 'consumed'
* result.
*
* Note: A parser does not always guarantee progress, i.e. if a small buffer was passed it may
* returns INPUT_PENDING with consumed == 0.
*
*/

Expand Down Expand Up @@ -93,13 +91,16 @@ class RedisParser {
PARSE_ARG_TYPE, // Parse [$:+-]
PARSE_ARG_S, // Parse string\r\n
BULK_STR_S,
SLASH_N_S,
CMD_COMPLETE_S,
};

State state_ = CMD_COMPLETE_S;
bool is_broken_token_ = false; // true, if a token (inline or bulk) is broken during the parsing.
bool server_mode_ = true;
uint8_t small_len_ = 0;
char arg_c_ = 0;

uint32_t bulk_len_ = 0;
uint32_t last_stashed_level_ = 0, last_stashed_index_ = 0;
uint32_t max_arr_len_;
Expand All @@ -114,6 +115,7 @@ class RedisParser {

using Blob = std::vector<uint8_t>;
std::vector<Blob> buf_stash_;
std::array<char, 32> small_buf_;
};

} // namespace facade
34 changes: 24 additions & 10 deletions src/facade/redis_parser_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -146,6 +146,19 @@ TEST_F(RedisParserTest, ClientMode) {

ASSERT_EQ(RedisParser::OK, Parse("-ERR foo bar\r\n"));
EXPECT_THAT(args_, ElementsAre(ErrArg("ERR foo")));

ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("_"));
EXPECT_EQ(1, consumed_);
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("\r"));
EXPECT_EQ(1, consumed_);
ASSERT_EQ(RedisParser::OK, Parse("\n"));
EXPECT_EQ(1, consumed_);
EXPECT_THAT(args_, ElementsAre(ArgType(RespExpr::NIL)));
ASSERT_EQ(RedisParser::OK, Parse("*2\r\n_\r\n_\r\n"));
ASSERT_EQ(10, consumed_);

ASSERT_EQ(RedisParser::OK, Parse("*3\r\n+OK\r\n$1\r\n1\r\n*2\r\n$1\r\n1\r\n$-1\r\n"));
ASSERT_THAT(args_, ElementsAre("OK", "1", ArrLen(2)));
}

TEST_F(RedisParserTest, Hierarchy) {
Expand Down Expand Up @@ -183,9 +196,9 @@ TEST_F(RedisParserTest, LargeBulk) {
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse(half));
ASSERT_EQ(512, consumed_);
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("\r"));
ASSERT_EQ(0, consumed_);
ASSERT_EQ(RedisParser::OK, Parse("\r\n"));
ASSERT_EQ(2, consumed_);
ASSERT_EQ(1, consumed_);
ASSERT_EQ(RedisParser::OK, Parse("\n"));
EXPECT_EQ(1, consumed_);

string part1 = absl::StrCat(prefix, half);
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse(part1));
Expand All @@ -208,7 +221,8 @@ TEST_F(RedisParserTest, LargeBulk) {
TEST_F(RedisParserTest, NILs) {
ASSERT_EQ(RedisParser::BAD_ARRAYLEN, Parse("_\r\n"));
parser_.SetClientMode();
ASSERT_EQ(RedisParser::OK, Parse("_\r\n"));
ASSERT_EQ(RedisParser::OK, Parse("_\r\nfooobar"));
EXPECT_EQ(3, consumed_);
}

TEST_F(RedisParserTest, NestedArray) {
Expand Down Expand Up @@ -245,15 +259,15 @@ TEST_F(RedisParserTest, UsedMemory) {

TEST_F(RedisParserTest, Eol) {
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("*1\r"));
EXPECT_EQ(1, consumed_);
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("1\r\n$5\r\n"));
EXPECT_EQ(7, consumed_);
EXPECT_EQ(3, consumed_);
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("\n$5\r\n"));
EXPECT_EQ(5, consumed_);
}

TEST_F(RedisParserTest, BulkSplit) {
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("*1\r\n$4\r\nSADD"));
ASSERT_EQ(12, consumed_);
ASSERT_EQ(RedisParser::OK, Parse("\r\n"));
ASSERT_EQ(RedisParser::INPUT_PENDING, Parse("*1\r\n$4\r\nSADD\r"));
ASSERT_EQ(13, consumed_);
ASSERT_EQ(RedisParser::OK, Parse("\n"));
}

TEST_F(RedisParserTest, InlineSplit) {
Expand Down
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