Implemented data packet history queue for storing packets sent/received by frontend and backend.

include/MySQL_Data_Stream.h

@@ -113,6 +113,8 @@ class MySQL_Data_Stream
 
 	PtrSizeArray *PSarrayIN;
 	PtrSizeArray *PSarrayOUT;
+	FixedSizeQueue data_packets_history_IN;
+	FixedSizeQueue data_packets_history_OUT;
 	//PtrSizeArray *PSarrayOUTpending;
 	PtrSizeArray *resultset;
 	unsigned int resultset_length;

include/MySQL_Thread.h

@@ -584,6 +584,7 @@ class MySQL_Threads_Handler
 		bool enable_server_deprecate_eof;
 		bool enable_load_data_local_infile;
 		bool log_mysql_warnings_enabled;
+		int data_packets_history_size;
 	} variables;
 	struct {
 		unsigned int mirror_sessions_current;

include/gen_utils.h

@@ -2,7 +2,7 @@
 #define __CLASS_PTR_ARRAY_H
 
 #include <memory>
-
+#include <queue>
 #include "proxysql.h"
 #include "sqlite3db.h"
 
@@ -189,6 +189,86 @@ class PtrSizeArray {
 		return intsize;
 	}
 };
+
+typedef struct {
+	void*  data = nullptr;
+	size_t len = 0;        
+	size_t capacity = 0;
+} buffer_t;
+
+class FixedSizeQueue : public std::queue<buffer_t> {
+private:
+	using std::queue<buffer_t>::push;
+	using std::queue<buffer_t>::emplace;
+	using std::queue<buffer_t>::swap;
+	size_t _max_size = 0;
+
+public:
+	FixedSizeQueue() = default;
+	FixedSizeQueue(size_t max_size) : _max_size(max_size) {}
+	~FixedSizeQueue() {
+		while (empty() == false) {
+			auto& node = front();
+			l_free(node.len, node.data);
+			pop();
+		}
+	}
+	
+	inline
+	size_t get_max_size() const {
+		return _max_size;
+	}
+
+	void set_max_size(size_t max_size) {
+		if (_max_size == max_size)
+			return;
+
+		_max_size = max_size;
+
+		if (size() > max_size) {
+			while (size() != max_size) {
+				auto& node = front();
+				l_free(node.len, node.data);
+				pop();
+			}
+		}
+	}
+
+	// using template here to create compile-time separate definition of push, one for true and one for false
+	template<bool ALLOC_MEM = true>
+	void push(void* buff, size_t len) {
+		if (_max_size == 0) return;
+		assert(buff && len);
+
+		buffer_t mybuff;
+
+		if (size() == _max_size) {
+			mybuff = front();
+			pop();
+		}
+
+		if (ALLOC_MEM == true) {
+			if (mybuff.capacity < len) {
+				if (mybuff.data) free(mybuff.data);
+
+				mybuff.data = l_alloc(len);
+				mybuff.capacity = len;
+			}
+
+			memcpy(mybuff.data, buff, len);
+			mybuff.len = len;
+
+		} else {
+			if (mybuff.data) free(mybuff.data);
+
+			mybuff.data = buff;
+			mybuff.capacity = mybuff.len = len;
+		}
+
+		emplace(mybuff);
+	}
+};
+
 #endif /* __CLASS_PTR_ARRAY_H */
 
 

include/proxysql_glovars.hpp

@@ -121,6 +121,7 @@ class ProxySQL_GlobalVariables {
 		char * ssl_key_pem_mem;
 		char * ssl_cert_pem_mem;
 		bool sqlite3_server;
+		int data_packets_history_size;
 #ifdef PROXYSQLCLICKHOUSE
 		bool clickhouse_server;
 #endif /* PROXYSQLCLICKHOUSE */

lib/MySQL_Thread.cpp

@@ -579,6 +579,7 @@ static char * mysql_thread_variables_names[]= {
 	(char *)"stats_time_backend_query",
 	(char *)"stats_time_query_processor",
 	(char *)"query_cache_stores_empty_result",
+	(char *)"data_packets_history_size",
 	NULL
 };
 
@@ -1198,6 +1199,7 @@ MySQL_Threads_Handler::MySQL_Threads_Handler() {
 	variables.enable_server_deprecate_eof=true;
 	variables.enable_load_data_local_infile=false;
 	variables.log_mysql_warnings_enabled=false;
+	variables.data_packets_history_size=0;
 	// status variables
 	status_variables.mirror_sessions_current=0;
 	__global_MySQL_Thread_Variables_version=1;
@@ -2081,6 +2083,16 @@ bool MySQL_Threads_Handler::set_variable(char *name, const char *value) {	// thi
 		}
 		return false;
 	}
+	if (!strcasecmp(name,"data_packets_history_size")) {
+		int intv=atoi(value);
+		if (intv >= 0 && intv < INT_MAX) {
+			variables.data_packets_history_size = intv;
+			GloVars.global.data_packets_history_size = intv;
+			return true;
+		} else {
+			return false;
+		}
+	}
 	return false;
 }
 
@@ -2259,7 +2271,7 @@ char ** MySQL_Threads_Handler::get_variables_list() {
 		VariablesPointers_int["binlog_reader_connect_retry_msec"] = make_tuple(&variables.binlog_reader_connect_retry_msec, 0, 0, true);
 		VariablesPointers_int["eventslog_format"] = make_tuple(&variables.eventslog_format, 0, 0, true);
 		VariablesPointers_int["wait_timeout"]     = make_tuple(&variables.wait_timeout,     0, 0, true);
-
+		VariablesPointers_int["data_packets_history_size"] = make_tuple(&variables.data_packets_history_size, 0, 0, true);
 
 	}
 

lib/ProxySQL_GloVars.cpp

@@ -144,6 +144,7 @@ ProxySQL_GlobalVariables::ProxySQL_GlobalVariables() :
 #endif
 
 	global.sqlite3_server=false;
+	global.data_packets_history_size=0;
 #ifdef PROXYSQLCLICKHOUSE
 	global.clickhouse_server=false;
 #endif /* PROXYSQLCLICKHOUSE */

lib/mysql_data_stream.cpp

@@ -141,8 +141,23 @@ static void __dump_pkt(const char *func, unsigned char *_ptr, unsigned int len)
 #define queue_r_ptr(_q) ((unsigned char *)_q.buffer+_q.tail)
 #define queue_w_ptr(_q) ((unsigned char *)_q.buffer+_q.head)
 
+#define add_to_data_packet_history(_o,_p,_s) if (unlikely(GloVars.global.data_packets_history_size)) { \
+	if (static_cast<int>(_o.get_max_size()) != GloVars.global.data_packets_history_size) { \
+		_o.set_max_size(GloVars.global.data_packets_history_size); \
+	} \
+	_o.push(_p,_s);\
+}
 
-
+// memory deallocation responsibility is now transferred to the queue as the buffer is directly assigned to it. 
+// if the size of data_packet_history is 0, the memory will be released.
+#define add_to_data_packet_history_without_alloc(_o,_p,_s) if (unlikely(GloVars.global.data_packets_history_size)) { \
+	if (static_cast<int>(_o.get_max_size()) != GloVars.global.data_packets_history_size) { \
+		_o.set_max_size(GloVars.global.data_packets_history_size); \
+	} \
+	_o.push<false>(_p,_s);\
+} else { \
+	l_free(_s,_p); \
+}
 //enum sslstatus { SSLSTATUS_OK, SSLSTATUS_WANT_IO, SSLSTATUS_FAIL};
 
 static enum sslstatus get_sslstatus(SSL* ssl, int n)
@@ -417,6 +432,11 @@ void MySQL_Data_Stream::init() {
 		if (PSarrayOUT==NULL) PSarrayOUT= new PtrSizeArray();
 //		if (PSarrayOUTpending==NULL) PSarrayOUTpending= new PtrSizeArray();
 		if (resultset==NULL) resultset = new PtrSizeArray();
+
+		if (unlikely(GloVars.global.data_packets_history_size)) {
+			data_packets_history_IN.set_max_size(GloVars.global.data_packets_history_size);
+			data_packets_history_OUT.set_max_size(GloVars.global.data_packets_history_size);
+		}
 	}
 	if (myds_type!=MYDS_FRONTEND) {
 		queue_destroy(queueIN);
@@ -941,6 +961,7 @@ int MySQL_Data_Stream::buffer2array() {
 			memcpy(queueIN.pkt.ptr, queue_r_ptr(queueIN) , queueIN.pkt.size);
 			queue_r(queueIN, queueIN.pkt.size);
 			PSarrayIN->add(queueIN.pkt.ptr,queueIN.pkt.size);
+			add_to_data_packet_history(data_packets_history_IN,queueIN.pkt.ptr,queueIN.pkt.size);
 			queueIN.pkt.ptr = NULL;
 		} else {
 			if (PSarrayIN->len == 0) {
@@ -951,6 +972,7 @@ int MySQL_Data_Stream::buffer2array() {
 				memcpy(queueIN.pkt.ptr, queue_r_ptr(queueIN) , queueIN.pkt.size);
 				queue_r(queueIN, queueIN.pkt.size);
 				PSarrayIN->add(queueIN.pkt.ptr,queueIN.pkt.size);
+				add_to_data_packet_history(data_packets_history_IN,queueIN.pkt.ptr,queueIN.pkt.size);
 				queueIN.pkt.ptr = NULL;
 			} else {
 				// get a pointer to the last entry in PSarrayIN
@@ -963,6 +985,7 @@ int MySQL_Data_Stream::buffer2array() {
 					memcpy(queueIN.pkt.ptr, queue_r_ptr(queueIN) , queueIN.pkt.size);
 					queue_r(queueIN, queueIN.pkt.size);
 					PSarrayIN->add(queueIN.pkt.ptr,queueIN.pkt.size);
+					add_to_data_packet_history(data_packets_history_IN,queueIN.pkt.ptr,queueIN.pkt.size);
 					queueIN.pkt.ptr = NULL;
 				} else {
 					// we append the packet at the end of the previous packet
@@ -1125,6 +1148,7 @@ int MySQL_Data_Stream::buffer2array() {
 			queueIN.pkt.ptr=NULL;
 		} else {
 			PSarrayIN->add(queueIN.pkt.ptr,queueIN.pkt.size);
+			add_to_data_packet_history(data_packets_history_IN,queueIN.pkt.ptr,queueIN.pkt.size);
 			pkts_recv++;
 			queueIN.pkt.size=0;
 			queueIN.pkt.ptr=NULL;
@@ -1245,7 +1269,8 @@ int MySQL_Data_Stream::array2buffer() {
 			if (PSarrayOUT->len-idx) {
 				proxy_debug(PROXY_DEBUG_PKT_ARRAY, 5, "Session=%p . DataStream: %p -- Removing a packet from array\n", sess, this);
 				if (queueOUT.pkt.ptr) {
-					l_free(queueOUT.pkt.size,queueOUT.pkt.ptr);
+					//l_free(queueOUT.pkt.size,queueOUT.pkt.ptr);
+					add_to_data_packet_history_without_alloc(data_packets_history_OUT,queueOUT.pkt.ptr,queueOUT.pkt.size);
 					queueOUT.pkt.ptr=NULL;
 				}
 		//VALGRIND_ENABLE_ERROR_REPORTING;
@@ -1290,7 +1315,8 @@ int MySQL_Data_Stream::array2buffer() {
 		ret=b;
 		if (queueOUT.partial==queueOUT.pkt.size) {
 			if (queueOUT.pkt.ptr) {
-				l_free(queueOUT.pkt.size,queueOUT.pkt.ptr);
+				//l_free(queueOUT.pkt.size,queueOUT.pkt.ptr);
+				add_to_data_packet_history_without_alloc(data_packets_history_OUT,queueOUT.pkt.ptr,queueOUT.pkt.size);
 				queueOUT.pkt.ptr=NULL;
 			}
 			proxy_debug(PROXY_DEBUG_PKT_ARRAY, 5, "Session=%p . DataStream: %p -- Packet completely written into send buffer\n", sess, this);