void NormalRepNode::masterOperations()
{
XmlManager& mgr = getManager();
XmlContainer& cont = getContainer();
XmlUpdateContext uc = mgr.createUpdateContext();
int num = documentNum;
XmlTransaction txn = mgr.createTransaction();
try {
ostringstream o;
printMsg("is putting document.");
for (int i = 0; i < num && (docNum_+i) < maxDocumentNum; i++) {
ostringstream o;
o << "<node>"
<< "<name>" << getEnvHome() << "</name>"
<< "<doc_id>" << i << "</doc_id>"
<< "</node>";
// Put documents
cont.putDocument(txn, "", o.str(), uc, DBXML_GEN_NAME);
}
docNum_ = cont.getNumDocuments(txn);
txn.commit();
printMsg("put document done.");
} catch (XmlException &xe) {
txn.abort();
// Deal with permission denied exception
if (xe.getExceptionCode() == XmlException::DATABASE_ERROR &&
xe.getDbErrno() == EACCES) {
yield();
} else
throwIfUnExpected(xe);
}
}
void doQuery( XmlTransaction &txn, XmlManager &db, const XmlContainer &container, const std::string &query )
{
////////////////////////////////////////////////////////////////////////
////// Performs a simple query (no context) against the ///////
////// provided container. ///////
////////////////////////////////////////////////////////////////////////
///// some defensive code eliminated for clarity //
// Perform the query. Result type is by default Result Document
std::string fullQuery = "collection('" + container.getName() + "')" + query;
try {
std::cout << "Exercising query '" << fullQuery << "' " << std::endl;
std::cout << "Return to continue: ";
getc(stdin);
XmlQueryContext context = db.createQueryContext();
XmlResults results( db.query( txn, fullQuery, context) );
XmlValue value;
while( results.next(value) ) {
// Obtain the value as a string and print it to stdout
std::cout << value.asString() << std::endl;
}
std::cout << (unsigned int) results.size()
<< " objects returned for expression '"
<< fullQuery << "'\n" << std::endl;
}
catch(XmlException &e) {
std::cerr << "Query " << fullQuery << " failed\n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
catch(std::exception &e) {
std::cerr << "Query " << fullQuery << " failed\n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
}
void replaceIndex( XmlContainer &container, const std::string &URI,
const std::string &nodeName, const std::string &indexType,
XmlTransaction &txn, XmlUpdateContext &uc)
{
std::cout << "Replacing index on node: " << nodeName << std::endl;
try
{
//Retrieve the XmlIndexSpecification from the container
XmlIndexSpecification idxSpec = container.getIndexSpecification( txn );
//Lets see what indexes exist on this container
std::string uri, name, index;
int count = 0;
std::cout << "Before index add." << std::endl;
while( idxSpec.next(uri, name, index) )
{
// Obtain the value as a string and print it to the console
std::cout << "\tFor node '" << name << "', found index: '" << index << "'." << std::endl;
count ++;
}
std::cout << count << " indexes found." << std::endl;
//Replace the indexes for the specified node
idxSpec.replaceIndex( URI, nodeName, indexType );
//Set the specification back to the container
container.setIndexSpecification( txn, idxSpec, uc );
//Look at the indexes again to make sure our replacement took.
count = 0;
idxSpec.reset();
std::cout << "After index add." << std::endl;
while( idxSpec.next(uri, name, index) )
{
// Obtain the value as a string and print it to the console
std::cout << "\tFor node '" << name << "', found index: '" << index << "'." << std::endl;
count ++;
}
std::cout << count << " indexes found." << std::endl;
}
//Catches XmlException
catch(std::exception &e)
{
std::cerr << "Index replace failed: \n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
std::cout << "Index replaced successfully." << std::endl;
}
void NormalRepNode::clientOperations()
{
XmlTransaction txn = getManager().createTransaction();
try {
// Save the new node state.
docNum_ = getContainer().getNumDocuments(txn);
txn.commit();
} catch (XmlException &xe) {
txn.abort();
throwIfUnExpected(xe);
}
}
void deleteIndex( XmlContainer &container, const std::string &URI,
const std::string &nodeName, const std::string &indexType,
XmlTransaction &txn, XmlUpdateContext &uc )
{
std::cout << "Deleting index type: '" << indexType << ""
<< " from node: '" << nodeName << "'." << std::endl;
try
{
//Retrieve the XmlIndexSpecification from the container
XmlIndexSpecification idxSpec = container.getIndexSpecification( txn );
std::cout << "Before the delete, the following indexes are maintained for the container:" << std::endl;
std::string uri, name, index;
while( idxSpec.next(uri, name, index) )
{
// Obtain the value as a string and print it to the console
std::cout << "\tFor node '" << name << "', found index: '" << index << "'." << std::endl;
}
std::cout << "\n" << std::endl;
//Delete the indexes from the specification.
idxSpec.deleteIndex( URI, nodeName, indexType );
//Set the specification back to the container
container.setIndexSpecification( txn, idxSpec, uc );
//Show the remaining indexes in the container, if any.
std::cout << "After the delete, the following indexes exist for the container:" << std::endl;
idxSpec.reset();
while( idxSpec.next(uri, name, index) )
{
// Obtain the value as a string and print it to the console
std::cout << "\tFor node '" << name << "', found index: '" << index << "'." << std::endl;
}
std::cout << "\n" << std::endl;
}
//Catches XmlException.
catch(std::exception &e)
{
std::cerr << "Index delete failed: \n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
std::cout << "Index deleted successfully.\n" << std::endl;
}
void getDetails( XmlTransaction &txn, XmlManager &mgr, const XmlContainer &container, const std::string &query, XmlQueryContext &context )
{
////////////////////////////////////////////////////////////////////////
////// Performs an query (in context) against the ///////
////// provided container. ///////
////////////////////////////////////////////////////////////////////////
///// some defensive code eliminated for clarity //
// Perform the query. Result type is by default Result Document
std::string fullQuery = "collection('" + container.getName() + "')" + query;
try {
std::cout << "Exercising query '" << fullQuery << "' " << std::endl;
std::cout << "Return to continue: ";
getc(stdin);
XmlResults results( mgr.query( txn, fullQuery, context ) );
XmlValue value;
std::cout << "\n\tProduct : Price : Inventory Level\n";
while( results.next(value) ) {
/// Retrieve the value as a document
XmlDocument theDocument = value.asDocument();
/// Obtain information of interest from the document. Note that the
// wildcard in the query expression allows us to not worry about what
// namespace this document uses.
std::string item = getValue( txn, mgr, theDocument, "fn:string(/*/product)", context);
std::string price = getValue( txn, mgr, theDocument, "fn:string(/*/inventory/price)", context);
std::string inventory = getValue( txn, mgr, theDocument, "fn:string(/*/inventory/inventory)", context);
std::cout << "\t" << item << " : " << price << " : " << inventory << std::endl;
}
std::cout << "\n";
std::cout << (unsigned int) results.size()
<< " objects returned for expression '"
<< fullQuery << "'\n" << std::endl;
}
//Catches XmlException
catch(std::exception &e) {
std::cerr << "Query " << fullQuery << " failed\n";
std::cerr << e.what() << "\n";
txn.abort();
exit(-1);
}
}
void doContextQuery( XmlTransaction &txn, XmlManager &mgr, const std::string cname,
const std::string &query, XmlQueryContext &context )
{
////////////////////////////////////////////////////////////////////////
////// Performs a simple query (with context) against the ///////
////// provided container. ///////
////////////////////////////////////////////////////////////////////////
///// some defensive code eliminated for clarity //
// Perform the query. Result type is by default Result Document
std::string fullQuery = "collection('" + cname + "')" + query;
try {
std::cout << "Exercising query '" << fullQuery << "' " << std::endl;
std::cout << "Return to continue: ";
getc(stdin);
std::cout << "\n";
XmlResults results( mgr.query(txn, fullQuery, context ) );
XmlValue value;
while(results.next(value)) {
// Get the document's name and print it to the console
XmlDocument theDocument = value.asDocument();
std::cout << "Document name: " << theDocument.getName() << std::endl;
std::cout << value.asString() << std::endl;
}
std::cout << (unsigned int)results.size()
<< " objects returned for expression '" << fullQuery
<< "'\n" << std::endl;
}
//Catches XmlException
catch(std::exception &e) {
std::cerr << "Query " << fullQuery << " failed\n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
}
//Get a document from the container using the document name
void doGetDocument( XmlTransaction &txn, XmlContainer &container, const std::string docname)
{
try {
std::cout << "Getting document '" << docname << "' from the container." << std::endl;
std::cout << "Return to continue: ";
getc(stdin);
std::cout << "\n";
//Get the document from the container using the document name
XmlDocument theDocument = container.getDocument(txn, docname);
std::string content;
std::cout << "Document name: " << theDocument.getName() << std::endl;
std::cout << theDocument.getContent(content) << std::endl;
}
//Catches XmlException
catch(std::exception &e) {
std::cerr << "Get document from container failed.\n";
std::cerr << e.what() << "\n";
txn.abort();
exit( -1 );
}
}
int
main(int argc, char **argv)
{
// This program uses a named container, which will apear
// on disk
std::string containerName = "people.dbxml";
std::string content = "<people><person><name>joe</name></person><person><name>mary</name></person></people>";
std::string docName = "people";
// Note that the query uses a variable, which must be set
// in the query context
std::string queryString =
"collection('people.dbxml')/people/person[name=$name]";
std::string environmentDir = ".";
// Berkeley DB environment flags
u_int32_t envFlags = DB_RECOVER|DB_CREATE|DB_INIT_MPOOL|
DB_INIT_LOCK|DB_INIT_TXN|DB_INIT_LOG;
// Berkeley DB cache size (25 MB). The default is quite small
u_int32_t envCacheSize = 25*1024*1024;
// argument parsing should really use getopt(), but
// avoid it for platform-independence
if (argc == 3) {
if (std::string(argv[1]) != std::string("-h"))
usage(argv[0]);
environmentDir = argv[2];
} else if (argc != 1)
usage(argv[0]);
// Create and open a Berkeley DB Transactional Environment.
int dberr;
DB_ENV *dbEnv = 0;
dberr = db_env_create(&dbEnv, 0);
if (dberr == 0) {
dbEnv->set_cachesize(dbEnv, 0, envCacheSize, 1);
dbEnv->set_errcall(dbEnv, errcall); // set error callback
dbEnv->set_lk_detect(dbEnv, DB_LOCK_DEFAULT); // handle deadlocks
dberr = dbEnv->open(dbEnv, environmentDir.c_str(), envFlags, 0);
}
if (dberr) {
std::cout << "Unable to create environment handle due to the following error: " <<
db_strerror(dberr) << std::endl;
if (dbEnv) dbEnv->close(dbEnv, 0);
return -1;
}
try {
// All BDB XML programs require an XmlManager instance.
// Create it from the DbEnv
XmlManager mgr(dbEnv, DBXML_ADOPT_DBENV);
// Because the container will exist on disk, remove it
// first if it exists
if (mgr.existsContainer(containerName))
mgr.removeContainer(containerName);
/* Create a container that is transactional. The container
* type is NodeContainer, which is the default container type,
* and the index is on nodes, which is the default for a
* NodeContainer container. XmlContainerConfig can be used
* to set the container type and index type.
*/
XmlContainerConfig config;
config.setTransactional(true);
XmlContainer cont = mgr.createContainer(
containerName,
config);
// All Container modification operations need XmlUpdateContext
XmlUpdateContext uc = mgr.createUpdateContext();
// The following putDocument call will auto-transact
// and will abort/cleanup if the operation deadlocks or
// otherwise fails
cont.putDocument(docName, content, uc);
// Querying requires an XmlQueryContext
XmlQueryContext qc = mgr.createQueryContext();
// Add a variable to the query context, used by the query
qc.setVariableValue("name", "mary");
// Use try/catch and while to handle deadlock/retry
int retry = 0;
while (retry < 5) { // hard-code 5 retries
// Create a new transaction for the query
XmlTransaction txn = mgr.createTransaction();
try {
// o Note the passing of txn to both methods
// o Often the XmlQueryExpression object will be created and
// saved for reuse in order to amortize the cost of parsing a query
XmlQueryExpression expr = mgr.prepare(txn, queryString, qc);
XmlResults res = expr.execute(txn, qc);
// Note use of XmlQueryExpression::getQuery() and
// XmlResults::size()
std::cout << "The query, '" << expr.getQuery() << "' returned " <<
(unsigned int)res.size() << " result(s)" << std::endl;
// Process results -- just print them
XmlValue value;
std::cout << "Result: " << std::endl;
while (res.next(value)) {
std::cout << "\t" << value.asString() << std::endl;
}
// done with the transaction
txn.commit();
break;
} catch (XmlException &x) {
txn.abort(); // unconditional
if ((x.getExceptionCode() == XmlException::DATABASE_ERROR) &&
(x.getDbErrno() == DB_LOCK_DEADLOCK)) {
++retry;
continue; // try again
}
throw; // re-throw -- not deadlock
}
}
// In C++, resources are released as objects go out
// of scope.
} catch (XmlException &xe) {
std::cout << "XmlException: " << xe.what() << std::endl;
}
return 0;
}
