Class Poco::Data::SQLChannel

File Information

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.