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alternator: eliminate regexes from the hot path

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This decreases the whole alternator::get_table cpu time by 78%
(from 2.8 us to 0.6 us on my cpu).

In perf_simple_query it decreases allocs/op by 1.6% (by removing 4 allocations)
and increases median tps by 3.4%.

Raw results from running:

./build/release/test/perf/perf_simple_query_g --smp 1 \
         --alternator forbid --default-log-level error \
         --random-seed=1235000092 --duration=180 --write

Before the patch:

median 46903.65 tps (197.2 allocs/op,  12.1 tasks/op,  170886 insns/op, 0 errors)
median absolute deviation: 210.15
maximum: 47354.59
minimum: 42535.63

After the patch:

median 48484.76 tps (194.1 allocs/op,  12.1 tasks/op,  168512 insns/op, 0 errors)
median absolute deviation: 317.32
maximum: 49247.69
minimum: 44656.38

Closes #12445
This commit is contained in:
Marcin Maliszkiewicz
2023-01-04 14:24:09 +01:00
committed by Nadav Har'El
parent 9029b8dead
commit 4c33791f96
1 changed files with 16 additions and 4 deletions
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20
alternator/executor.cc
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@@ -127,6 +127,20 @@ void executor::supplement_table_info(rjson::value& descr, const schema& schema,
// See https://github.com/scylladb/scylla/issues/4480
static constexpr int max_table_name_length = 222;
static bool valid_table_name_chars(std::string_view name) {
for (auto c : name) {
if ((c < 'a' || c > 'z') &&
(c < 'A' || c > 'Z') &&
(c < '0' || c > '9') &&
c != '_' &&
c != '-' &&
c != '.') {
return false;
}
}
return true;
}
// The DynamoDB developer guide, https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.NamingRules
// specifies that table names "names must be between 3 and 255 characters long
// and can contain only the following characters: a-z, A-Z, 0-9, _ (underscore), - (dash), . (dot)
@@ -136,8 +150,7 @@ static void validate_table_name(const std::string& name) {
throw api_error::validation(
format("TableName must be at least 3 characters long and at most {} characters long", max_table_name_length));
}
static const std::regex valid_table_name_chars ("[a-zA-Z0-9_.-]*");
if (!std::regex_match(name.c_str(), valid_table_name_chars)) {
if (!valid_table_name_chars(name)) {
throw api_error::validation(
"TableName must satisfy regular expression pattern: [a-zA-Z0-9_.-]+");
}
@@ -153,11 +166,10 @@ static void validate_table_name(const std::string& name) {
// The view_name() function assumes the table_name has already been validated
// but validates the legality of index_name and the combination of both.
static std::string view_name(const std::string& table_name, std::string_view index_name, const std::string& delim = ":") {
static const std::regex valid_index_name_chars ("[a-zA-Z0-9_.-]*");
if (index_name.length() < 3) {
throw api_error::validation("IndexName must be at least 3 characters long");
}
if (!std::regex_match(index_name.data(), valid_index_name_chars)) {
if (!valid_table_name_chars(index_name)) {
throw api_error::validation(
format("IndexName '{}' must satisfy regular expression pattern: [a-zA-Z0-9_.-]+", index_name));
}