Description:
The problem manifests itself only on big-endian platforms. As documented in the Ndb.hpp header file, the Interpreted programs are executed in a register-based virtual machine. The virtual machine has eight 64 bit registers numbered 0-7. The write_attr operation writes a register value into an attribute. If the attribute is a 32-bit integer then the first 32 bit of the 64-bit value are taken from the register. On little-endian platforms this is OK, but on big-endian platforms the 4 most significant bytes are taken and this is wrong.
How to repeat:
Below is a small program that illustrates the problem. At the end, the program prints "LOCK_FLAG=0x1020304". This is wrong. The correct result should be "LOCK_FLAG=0x5060708".
/*
Create the following table in the test database:
use test;
CREATE TABLE call_context (
CONTEXT_ID INT NOT NULL,
VERSION INT DEFAULT 3000000 NOT NULL,
LOCK_FLAG INT UNSIGNED NOT NULL,
LOCK_TIME INT UNSIGNED NOT NULL,
LOCK_TIME_USEC INT UNSIGNED NOT NULL,
CONTEXT_DATA VARBINARY(4000) NOT NULL,
PRIMARY KEY (CONTEXT_ID)
) ENGINE=NDBCLUSTER;
insert into call_context values (1, 3000000, 11, unix_timestamp(now()), 777, '\0\0\0\0');
*/
#include <NdbApi.hpp>
#include <stdio.h>
#include <iostream.h>
#include <time.h>
#include <vector>
#define PRINT_ERROR(code,msg) \
cout << "Error in " << __FILE__ << ", line: " << __LINE__ \
<< ", code: " << code \
<< ", msg: " << msg << "." << endl
#define APIERROR(error) { \
PRINT_ERROR(error.code,error.message); \
exit(-1); }
static void run_application(Ndb_cluster_connection &cluster_connection);
int main(int argc, char* argv[])
{
// ndb_init must be called first
ndb_init();
printf("NDB library initialized\n");
// connect to mysql server and cluster and run application
{
// Object representing the cluster
Ndb_cluster_connection cluster_connection("nodeid=9,localhost:1186");
// Connect to cluster management server (ndb_mgmd)
if (cluster_connection.connect(4 /* retries */,
5 /* delay between retries */,
1 /* verbose */))
{
cout << "Cluster management server was not ready within 30 secs.\n";
exit(1);
}
printf("Connected to the management server\n");
// Optionally connect and wait for the storage nodes (ndbd's)
if (cluster_connection.wait_until_ready(30, 0) < 0)
{
cout << "Cluster was not ready within 30 secs.\n";
exit(1);
}
printf("Cluster is ready\n");
run_application(cluster_connection);
}
ndb_end(0);
return 0;
}
static void do_readWithLock(Ndb &myNdb);
static void run_application(Ndb_cluster_connection &cluster_connection)
{
// Connect to database via NdbApi
// Object representing the database
Ndb myNdb( &cluster_connection, "test" );
if (myNdb.init())
{
APIERROR(myNdb.getNdbError());
}
printf("Connected to the \"test\" database\n");
do_readWithLock(myNdb);
}
static void do_readWithLock(Ndb &myNdb)
{
const NdbDictionary::Dictionary* myDict = myNdb.getDictionary();
const NdbDictionary::Table *myTable = myDict->getTable("call_context");
if (myTable == NULL)
APIERROR(myDict->getNdbError());
{
// Indexes
NdbDictionary::Dictionary::List lst;
int res = myDict->listIndexes(lst, "call_context");
if (res < 0)
APIERROR(myDict->getNdbError());
cout << "Number of indexes=" << lst.count << endl;
for (int i = 0; i < lst.count; i++)
{
cout << "Index " << i << " name=<" << lst.elements[i].name << ">" << endl;
}
}
vector<char> contextData(myTable->getColumn("CONTEXT_DATA")->getLength() + 2);
NdbTransaction *myTransaction = myNdb.startTransaction();
if (myTransaction == NULL) APIERROR(myNdb.getNdbError());
NdbOperation *myOperation = myTransaction->getNdbOperation(myTable);
if (myOperation == NULL) APIERROR(myTransaction->getNdbError());
if (myOperation->interpretedUpdateTuple()) APIERROR(myTransaction->getNdbError());
if (myOperation->equal("CONTEXT_ID", 1)) APIERROR(myTransaction->getNdbError());
if (
myOperation->load_const_u64(1, (Uint64)0x0102030405060708) == -1 || // Reg1 = 0x0102030405060708
myOperation->write_attr("LOCK_FLAG", 1) == -1 // LOCK_FLAG = Reg1
) APIERROR(myOperation->getNdbError());
NdbRecAttr *lockFlagAttr = myOperation->getValue("LOCK_FLAG", NULL);
if (lockFlagAttr == NULL) APIERROR(myTransaction->getNdbError());
if (myTransaction->execute( NdbTransaction::Commit ) == -1)
APIERROR(myTransaction->getNdbError());
cout << "LOCK_FLAG=0x" << hex << (unsigned)lockFlagAttr->u_32_value() << dec << endl;
myNdb.closeTransaction(myTransaction);
}
Suggested fix:
File mysql-5.0.21\ndb\src\kernel\blocks\dbtup\DbtupExecQuery.cpp, from line 1552:
TdataForUpdate[1] = TregMemBuffer[theRegister + 2];
TdataForUpdate[2] = TregMemBuffer[theRegister + 3];
The suggested fix is:
if (TattrNoOfWords == 1) {
TdataForUpdate[1] = (Uint32)* (Int64*)(TregMemBuffer + theRegister + 2);
} else {
TdataForUpdate[1] = TregMemBuffer[theRegister + 2];
TdataForUpdate[2] = TregMemBuffer[theRegister + 3];
}
Short explanation of the fix:
The array TregMemBuffer is the memory area for the 64-bit registers 0-7. Four 32-bit words are used for each register. The first word is for the type of the value (0 - NULL, 0x50 - 32-bit value, 0x60 - 64-bit value); the second word is not really used and exists there just as a padding to avoid the possible SIG_BUS signals when working with the 64-bit value that follows; the third and fourth words contain the 64-bit value. Variable theRegister contains the virtual register number multiplied by 4 (i.e. 12 for register 3).
The two lines of code (1552 and 1553) copy the 64-bit value from the register area into the TdataForUpdate array which is just a data structure needed for the updateAttributes function. As you can see, two 32-bit words are always copied into the TdataForUpdate array, even if the attribute is a 32-bit integer. But when the attribute is a single 32-bit integer word, then only one word of the value is used and the second is ignored. On little-endian platforms it happens that the correct word is used, but on big-endian the wrong word is used. The suggested fix is to check if the attribute to be updated is a 32-bit value, and if so, then cast the 64-bit value of the register into the 32-bit value and put this single value into the TdataForUpdate array.
The fix was tested in our HP-UX 11.11 environment and worked fine.
Description: The problem manifests itself only on big-endian platforms. As documented in the Ndb.hpp header file, the Interpreted programs are executed in a register-based virtual machine. The virtual machine has eight 64 bit registers numbered 0-7. The write_attr operation writes a register value into an attribute. If the attribute is a 32-bit integer then the first 32 bit of the 64-bit value are taken from the register. On little-endian platforms this is OK, but on big-endian platforms the 4 most significant bytes are taken and this is wrong. How to repeat: Below is a small program that illustrates the problem. At the end, the program prints "LOCK_FLAG=0x1020304". This is wrong. The correct result should be "LOCK_FLAG=0x5060708". /* Create the following table in the test database: use test; CREATE TABLE call_context ( CONTEXT_ID INT NOT NULL, VERSION INT DEFAULT 3000000 NOT NULL, LOCK_FLAG INT UNSIGNED NOT NULL, LOCK_TIME INT UNSIGNED NOT NULL, LOCK_TIME_USEC INT UNSIGNED NOT NULL, CONTEXT_DATA VARBINARY(4000) NOT NULL, PRIMARY KEY (CONTEXT_ID) ) ENGINE=NDBCLUSTER; insert into call_context values (1, 3000000, 11, unix_timestamp(now()), 777, '\0\0\0\0'); */ #include <NdbApi.hpp> #include <stdio.h> #include <iostream.h> #include <time.h> #include <vector> #define PRINT_ERROR(code,msg) \ cout << "Error in " << __FILE__ << ", line: " << __LINE__ \ << ", code: " << code \ << ", msg: " << msg << "." << endl #define APIERROR(error) { \ PRINT_ERROR(error.code,error.message); \ exit(-1); } static void run_application(Ndb_cluster_connection &cluster_connection); int main(int argc, char* argv[]) { // ndb_init must be called first ndb_init(); printf("NDB library initialized\n"); // connect to mysql server and cluster and run application { // Object representing the cluster Ndb_cluster_connection cluster_connection("nodeid=9,localhost:1186"); // Connect to cluster management server (ndb_mgmd) if (cluster_connection.connect(4 /* retries */, 5 /* delay between retries */, 1 /* verbose */)) { cout << "Cluster management server was not ready within 30 secs.\n"; exit(1); } printf("Connected to the management server\n"); // Optionally connect and wait for the storage nodes (ndbd's) if (cluster_connection.wait_until_ready(30, 0) < 0) { cout << "Cluster was not ready within 30 secs.\n"; exit(1); } printf("Cluster is ready\n"); run_application(cluster_connection); } ndb_end(0); return 0; } static void do_readWithLock(Ndb &myNdb); static void run_application(Ndb_cluster_connection &cluster_connection) { // Connect to database via NdbApi // Object representing the database Ndb myNdb( &cluster_connection, "test" ); if (myNdb.init()) { APIERROR(myNdb.getNdbError()); } printf("Connected to the \"test\" database\n"); do_readWithLock(myNdb); } static void do_readWithLock(Ndb &myNdb) { const NdbDictionary::Dictionary* myDict = myNdb.getDictionary(); const NdbDictionary::Table *myTable = myDict->getTable("call_context"); if (myTable == NULL) APIERROR(myDict->getNdbError()); { // Indexes NdbDictionary::Dictionary::List lst; int res = myDict->listIndexes(lst, "call_context"); if (res < 0) APIERROR(myDict->getNdbError()); cout << "Number of indexes=" << lst.count << endl; for (int i = 0; i < lst.count; i++) { cout << "Index " << i << " name=<" << lst.elements[i].name << ">" << endl; } } vector<char> contextData(myTable->getColumn("CONTEXT_DATA")->getLength() + 2); NdbTransaction *myTransaction = myNdb.startTransaction(); if (myTransaction == NULL) APIERROR(myNdb.getNdbError()); NdbOperation *myOperation = myTransaction->getNdbOperation(myTable); if (myOperation == NULL) APIERROR(myTransaction->getNdbError()); if (myOperation->interpretedUpdateTuple()) APIERROR(myTransaction->getNdbError()); if (myOperation->equal("CONTEXT_ID", 1)) APIERROR(myTransaction->getNdbError()); if ( myOperation->load_const_u64(1, (Uint64)0x0102030405060708) == -1 || // Reg1 = 0x0102030405060708 myOperation->write_attr("LOCK_FLAG", 1) == -1 // LOCK_FLAG = Reg1 ) APIERROR(myOperation->getNdbError()); NdbRecAttr *lockFlagAttr = myOperation->getValue("LOCK_FLAG", NULL); if (lockFlagAttr == NULL) APIERROR(myTransaction->getNdbError()); if (myTransaction->execute( NdbTransaction::Commit ) == -1) APIERROR(myTransaction->getNdbError()); cout << "LOCK_FLAG=0x" << hex << (unsigned)lockFlagAttr->u_32_value() << dec << endl; myNdb.closeTransaction(myTransaction); } Suggested fix: File mysql-5.0.21\ndb\src\kernel\blocks\dbtup\DbtupExecQuery.cpp, from line 1552: TdataForUpdate[1] = TregMemBuffer[theRegister + 2]; TdataForUpdate[2] = TregMemBuffer[theRegister + 3]; The suggested fix is: if (TattrNoOfWords == 1) { TdataForUpdate[1] = (Uint32)* (Int64*)(TregMemBuffer + theRegister + 2); } else { TdataForUpdate[1] = TregMemBuffer[theRegister + 2]; TdataForUpdate[2] = TregMemBuffer[theRegister + 3]; } Short explanation of the fix: The array TregMemBuffer is the memory area for the 64-bit registers 0-7. Four 32-bit words are used for each register. The first word is for the type of the value (0 - NULL, 0x50 - 32-bit value, 0x60 - 64-bit value); the second word is not really used and exists there just as a padding to avoid the possible SIG_BUS signals when working with the 64-bit value that follows; the third and fourth words contain the 64-bit value. Variable theRegister contains the virtual register number multiplied by 4 (i.e. 12 for register 3). The two lines of code (1552 and 1553) copy the 64-bit value from the register area into the TdataForUpdate array which is just a data structure needed for the updateAttributes function. As you can see, two 32-bit words are always copied into the TdataForUpdate array, even if the attribute is a 32-bit integer. But when the attribute is a single 32-bit integer word, then only one word of the value is used and the second is ignored. On little-endian platforms it happens that the correct word is used, but on big-endian the wrong word is used. The suggested fix is to check if the attribute to be updated is a 32-bit value, and if so, then cast the 64-bit value of the register into the 32-bit value and put this single value into the TdataForUpdate array. The fix was tested in our HP-UX 11.11 environment and worked fine.