Library: Data
Package: Logging
Header: Poco/Data/SQLChannel.h
Description
This Channel implements logging to a SQL database. The channel is dependent on the schema. The DDL for table creation (subject to target DDL dialect dependent modifications) is:
"CREATE TABLE T_POCO_LOG (Source VARCHAR, Name VARCHAR, ProcessId INTEGER, Thread VARCHAR, ThreadId INTEGER, Priority INTEGER, Text VARCHAR, DateTime DATE)"
The table name is configurable through "table" property. Other than DateTime filed name used for optional time-based archiving purposes, currently the field names are not mandated. However, it is recomended to use names as specified above.
To provide as non-intrusive operation as possbile, the log entries are cached and inserted into the target database asynchronously by default. The blocking, however, will occur before the next entry insertion with default timeout of 1 second. The default settings can be overridden (see async, timeout and throw properties for details). If throw property is false, insertion timeouts are ignored, otherwise a TimeoutException is thrown. To force insertion of every entry, set timeout to 0. This setting, however, introduces a risk of long blocking periods in case of remote server communication delays.
Inheritance
Direct Base Classes: Poco::Channel, Poco::Runnable
All Base Classes: Poco::Channel, Poco::Configurable, Poco::RefCountedObject, Poco::Runnable
Member Summary
Member Functions: close, getProperty, isRunning, log, logged, open, registerChannel, run, setProperty, stop, wait
Inherited Functions: close, duplicate, getProperty, log, open, referenceCount, release, run, setProperty
Nested Classes
class LogNotification
Constructors
SQLChannel
SQLChannel();
Creates SQLChannel.
SQLChannel
SQLChannel(
const std::string & connector,
const std::string & connect,
const std::string & name = "-",
const std::string & table = "T_POCO_LOG",
int timeout = 1000,
int minBatch = DEFAULT_MIN_BATCH_SIZE,
int maxBatch = DEFAULT_MAX_BATCH_SIZE
);
Creates an SQLChannel with the given connector, connect string, timeout, table and name. The connector must be already registered.
Destructor
~SQLChannel
~SQLChannel();
Member Functions
close
void close();
Closes the SQLChannel.
See also: Poco::Channel::close()
getProperty
std::string getProperty(
const std::string & name
) const;
Returns the value of the property with the given name.
See also: Poco::Channel::getProperty()
isRunning
bool isRunning() const;
Returns true if the logging thread is running.
log
void log(
const Message & msg
);
Writes the log message to the database.
See also: Poco::Channel::log()
logged
size_t logged() const;
Returns the number of logged entries.
open
void open();
Opens the SQLChannel. Returns true if succesful.
See also: Poco::Channel::open()
registerChannel
static void registerChannel();
Registers the channel with the global LoggingFactory.
run
void run();
Dequeues and sends the logs to the DB.
See also: Poco::Runnable::run()
setProperty
void setProperty(
const std::string & name,
const std::string & value
);
Sets the property with the given value.
The following properties are supported:
- name: The name used to identify the source of log messages. Defaults to "-".
- connector: The target data storage connector name.
- connect: The target data storage connection string.
- table: Destination log table name. Defaults to "T_POCO_LOG". Table must exist in the target database.
- keep: Max row age for the log table. To disable archiving, set this property to empty string or "forever".
- archive: Archive table name. Defaults to "T_POCO_LOG_ARCHIVE". Table must exist in the target database. To disable archiving, set this property to empty string.
- async: Indicates asynchronous execution. When excuting asynchronously, messages are sent to the target using asyncronous execution. However, prior to the next message being processed and sent to the target, the previous operation must have been either completed or timed out (see timeout and throw properties for details on how abnormal conditos are handled). This property is deprecated and has no effect - all logging is asynchronous since the 1.13.0. release.
- timeout: Timeout (ms) to wait for previous log operation completion. Values "0" and "" mean no timeout. Only valid when logging is asynchronous, otherwise ignored.
- throw: Boolean value indicating whether to throw in case of timeout. Setting this property to false may result in log entries being lost. True values are (case insensitive) "true", "t", "yes", "y". Anything else yields false.
- minBatch: Minimal number of log entries to accumulate before actually sending logs to the destination. Defaults to 1 entry (for compatibility with older versions); can't be zero or larger than maxBatch.
- maxBatch: Maximum number of log entries to accumulate. When the log queue reaches this size, log entries are silently discarded. Defaults to 100, can't be zero or larger than 1000.
- bulk: Do bulk execute (on most DBMS systems, this can speed up things drastically).
- file Destination file name for the backup FileChannel, used when DB connection is not present to log not executed SQL statements.
See also: Poco::Channel::setProperty()
stop
void stop();
Stops and joins the logging thread..
wait
std::size_t wait(
int ms = 1000
);
Waits for the completion of the previous operation and returns the result. If chanel is in synchronous mode, returns 0 immediately.
Variables
DEFAULT_MAX_BATCH_SIZE
static const int DEFAULT_MAX_BATCH_SIZE = 1000;
DEFAULT_MIN_BATCH_SIZE
static const int DEFAULT_MIN_BATCH_SIZE = 1;
PROP_ARCHIVE_TABLE
static const std::string PROP_ARCHIVE_TABLE;
PROP_ASYNC
static const std::string PROP_ASYNC;
PROP_BULK
static const std::string PROP_BULK;
PROP_CONNECT
static const std::string PROP_CONNECT;
PROP_CONNECTOR
static const std::string PROP_CONNECTOR;
PROP_FILE
static const std::string PROP_FILE;
PROP_MAX_AGE
static const std::string PROP_MAX_AGE;
PROP_MAX_BATCH
static const std::string PROP_MAX_BATCH;
PROP_MIN_BATCH
static const std::string PROP_MIN_BATCH;
PROP_NAME
static const std::string PROP_NAME;
PROP_TABLE
static const std::string PROP_TABLE;
PROP_THROW
static const std::string PROP_THROW;
PROP_TIMEOUT
static const std::string PROP_TIMEOUT;