Bug#34833913 binlog_transaction_compression_level_zstd has no effect

PROBLEM :

Setting of the 'binlog_transaction_compression_level_zstd' variable has no effect.
Size of data compressed with ZSTD library does not change, even if we
increase compression level value up to 22.

Solution :

1. Need to call function Zstd_comp::set_compression_level() in
   setup_compressor().
2. Reset m_started variable to false in Zstd_comp::do_finish()
   function since reset_compressor() function is not called.

Change-Id: Ib9dcfbda9e15fae49ea6828802eac3cb73e46c9a

libbinlogevents/src/compression/zstd_comp.cpp

@@ -166,7 +166,7 @@ Compress_status Zstd_comp::do_finish(Managed_buffer_sequence_t &out) {
     move_position(out, obuf.pos);
   } while (zstd_status > 0);
   BAPI_LOG("info", BAPI_VAR(m_ibuf.pos) << " " << BAPI_VAR(m_ibuf.size));
-
+  m_started = false;
   return Compress_status::success;
 }
 

mysql-test/suite/binlog/r/binlog_trx_compression_level_zstd_no_effect.result

@@ -0,0 +1,45 @@
+#
+# 1) Prepare a sample table
+#
+CREATE TABLE t (a LONGTEXT);
+#
+# 2) Enable binlog_transaction_compression
+#
+SET @@session.binlog_transaction_compression = ON;
+#
+# 3) Set the value of binlog_transaction_compression_level_zstd to 1
+#
+SET @@session.binlog_transaction_compression_level_zstd = 1;
+#
+# 4) Save the binlog position before and after inserting the values in table
+#
+include/save_binlog_position.inc
+INSERT INTO t VALUES (LOAD_FILE('../../std_data/mysqldump_57.sql'));
+include/save_binlog_position.inc
+#
+# 5) Compute the compressed size for binlog_transaction_compression_level
+#_zstd = 1
+#
+#
+# 6) Set the value of binlog_transaction_compression_level_zstd to 19
+#
+SET @@session.binlog_transaction_compression_level_zstd = 19;
+#
+# 7) Save the binlog position before and after inserting the values in table
+#
+include/save_binlog_position.inc
+INSERT INTO t VALUES (LOAD_FILE('../../std_data/mysqldump_57.sql'));
+include/save_binlog_position.inc
+#
+# 8) Compute the compressed size for binlog_transaction_compression_level
+#_zstd = 19
+#
+#
+# 9) Check that the compressed size for level 19 should be smaller than level 1
+#
+include/assert.inc [The compresed size for level 19 should be smaller then level 1]
+#
+# 10) Cleanup.
+#
+DROP TABLE t;
+SET SESSION binlog_transaction_compression_level_zstd = SAVED;

mysql-test/suite/binlog/t/binlog_trx_compression_level_zstd_no_effect.test

@@ -0,0 +1,115 @@
+###############################################################################
+# === Purpose ===
+#
+# The pupose of this test is to verify that the session variable
+# binlog_transaction_compression_level_zstd is working as expected. It checks
+# that the size of payload is compressed on increasing the value of
+# binlog_transaction_compression_level_zstd.
+#
+# === Requirements ===
+#
+# 1. The compressed size for higher value of binlog_transaction_compression_level_zstd
+#    should be less than the compressed size for smaller value of binlog_transaction_
+#    compression_level_zstd
+#
+# === Implementation ===
+#
+#  1) Prepare a sample table
+#  2) Enable binlog_transaction_compression
+#  3) Set the value of binlog_transaction_compression_level_zstd to 1
+#  4) Save the binlog position before and after inserting the values in table
+#  5) Compute the compressed size for binlog_transaction_compression_level = 1
+#  6) Set the value of binlog_transaction_compression_level_zstd to 19
+#  7) Save the binlog position before and after inserting the values in table
+#  8) Compute the compressed size for binlog_transaction_compression_level = 19
+#  9) Check that the compressed size for level 19 should be smaller than level 1
+#  10) Cleanup.
+#
+# === Reference ===
+#
+# Bug#34833913 : binlog_transaction_compression_level_zstd has no effect
+#
+###############################################################################
+
+
+--source include/have_log_bin.inc
+--source include/have_binlog_format_row.inc
+
+--echo #
+--echo # 1) Prepare a sample table
+--echo #
+
+CREATE TABLE t (a LONGTEXT);
+
+--echo #
+--echo # 2) Enable binlog_transaction_compression
+--echo #
+
+SET @@session.binlog_transaction_compression = ON;
+--let $saved_binlog_transaction_compression_level_zstd_session = `SELECT @@SESSION.binlog_transaction_compression_level_zstd`
+
+--echo #
+--echo # 3) Set the value of binlog_transaction_compression_level_zstd to 1
+--echo #
+
+SET @@session.binlog_transaction_compression_level_zstd = 1;
+
+--echo #
+--echo # 4) Save the binlog position before and after inserting the values in table
+--echo #
+
+--source include/save_binlog_position.inc
+--let $binlog_start_1 = $binlog_position
+
+INSERT INTO t VALUES (LOAD_FILE('../../std_data/mysqldump_57.sql'));
+
+--source include/save_binlog_position.inc
+--let $binlog_end_1 = $binlog_position
+
+--echo #
+--echo # 5) Compute the compressed size for binlog_transaction_compression_level_zstd = 1
+--echo #
+
+
+--expr $compressed_size_1 = $binlog_end_1 - $binlog_start_1
+
+--echo #
+--echo # 6) Set the value of binlog_transaction_compression_level_zstd to 19
+--echo #
+
+SET @@session.binlog_transaction_compression_level_zstd = 19;
+
+--echo #
+--echo # 7) Save the binlog position before and after inserting the values in table
+--echo #
+
+--source include/save_binlog_position.inc
+--let $binlog_start_2 = $binlog_position
+
+INSERT INTO t VALUES (LOAD_FILE('../../std_data/mysqldump_57.sql'));
+
+--source include/save_binlog_position.inc
+--let $binlog_end_2 = $binlog_position
+
+--echo #
+--echo # 8) Compute the compressed size for binlog_transaction_compression_level
+--echo #_zstd = 19
+--echo #
+
+--expr $compressed_size_2 = $binlog_end_2 - $binlog_start_2
+
+--echo #
+--echo # 9) Check that the compressed size for level 19 should be smaller than level 1
+--echo #
+
+--let $assert_text = The compresed size for level 19 should be smaller then level 1
+--let $assert_cond = $compressed_size_1 > $compressed_size_2
+--source include/assert.inc
+
+--echo #
+--echo # 10) Cleanup.
+--echo #
+DROP TABLE t;
+--replace_result $saved_binlog_transaction_compression_level_zstd_session SAVED
+--eval SET SESSION binlog_transaction_compression_level_zstd = $saved_binlog_transaction_compression_level_zstd_session
+

sql/binlog.cc

@@ -64,6 +64,7 @@
 #include "libbinlogevents/include/buffer/grow_calculator.h"
 #include "libbinlogevents/include/compression/compressor.h"
 #include "libbinlogevents/include/compression/payload_event_buffer_istream.h"
+#include "libbinlogevents/include/compression/zstd_comp.h"
 #include "libbinlogevents/include/control_events.h"
 #include "libbinlogevents/include/debug_vars.h"
 #include "libbinlogevents/include/rows_event.h"
@@ -2099,14 +2100,20 @@ class Binlog_cache_compressor {
   }
 
   /// Get and configure the compressor; update m_compressor.
-  ///
+  /// Set the compression_level for m_compressor
   /// @return true on error, false on success.
   [[NODISCARD]] bool setup_compressor() {
     m_compressor = m_context.get_compressor(&m_thd);
     if (m_compressor == nullptr) {
       DBUG_PRINT("info", ("fallback to uncompressed: compressor==nullptr"));
       return true;
     }
+    auto zstd_ptr = std::dynamic_pointer_cast<
+        binary_log::transaction::compression::Zstd_comp>(m_compressor);
+    if (zstd_ptr) {
+      zstd_ptr->set_compression_level(
+          m_thd.variables.binlog_trx_compression_level_zstd);
+    }
     // Allow compressor to optimize space usage based on uncompressed
     // size.
     m_compressor->set_pledged_input_size(m_uncompressed_size);
@@ -2199,7 +2206,6 @@ class Binlog_cache_compressor {
     }
     return false;
   }
-
   /// Session context.
   THD &m_thd;
   /// Transaction cache.