Bz2 Chilkat2 Perl Reference Documentation
Chilkat2::Bz2
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
Chilkat.Bz2 provides BZip2 compression and decompression for files, memory buffers, and BinData. It can create standard .bz2 file images, decompress .bz2 content back to its original bytes, and support abortable long-running operations.
For an extended overview, see Bz2 Class Overview
Object Creation
use Chilkat2;
my $bz2 = Chilkat2::Bz2->new;
# or set properties (and RaiseError) at creation:
# my $bz2 = Chilkat2::Bz2->new(VerboseLogging => 1, RaiseError => 1);Creates the object. The optional pairs set writable properties (and RaiseError) in order, as if set one by one; an unknown or read-only name croaks. use Chilkat2; loads every class; the Chilkat2/Bz2.pm file holds only this class's documentation (perldoc Chilkat2::Bz2).
Perl frees the object when its last reference goes (undef $bz2, or the variable going out of scope); there is nothing to close. Objects returned by methods are independent and freed the same way. The class may be subclassed (use parent -norequire, 'Chilkat2::Bz2';): an object is a blessed hash reference whose hash is free for the subclass's own fields.
When false (the default), a method that fails returns false (or undef), and the reason is in LastErrorText. When true, it dies with a Chilkat2::Error instead, as DBI does with its RaiseError. Objects returned by a method inherit the value of the object that returned them.
Errors
A Chilkat2::Error stringifies to the failed call's full LastErrorText, and has the methods text, class ('Chilkat2::Bz2'), method (the method name) and object. Methods that look something up and find nothing return undef without dying (each such method says so), methods that answer a question (HasMember, IsUnlocked, ...) return a plain boolean, and property reads and writes never fail for Chilkat reasons.
Misuse always croaks, with your file and line, whatever RaiseError is: a wrong number of arguments, a reference or undef where a string or number is expected, an object of the wrong class, an out-of-range integer, a string containing a NUL character, a wide character in a byte string, or a write to a read-only property.
Strings are Perl character strings in both directions (length, regexes and :encoding layers see characters); binary data (BinData) is a byte string. Unlocking: call Chilkat2::Global->new->UnlockBundle('...') once at startup.
Properties
AbortCurrent
my $boolVal = $bz2->AbortCurrent;
$bz2->AbortCurrent($boolVal);
Set this property to 1
A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to 0
LastErrorText to determine the final outcome.DebugLogFilePath
my $strVal = $bz2->DebugLogFilePath;
$bz2->DebugLogFilePath($strVal);
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
HeartbeatMs
my $intVal = $bz2->HeartbeatMs;
$bz2->HeartbeatMs($intVal);
Specifies the interval, in milliseconds, between AbortCheck event callbacks during supported long-running compression and decompression operations. The default is 0, which disables AbortCheck callbacks.
Set a positive value, such as 200, when the application needs periodic opportunities to request cancellation. The interval is approximate; callbacks occur only while an operation is at a point where progress events can be delivered.
AbortCheck handler, set the callback's abort value to request termination. A synchronous method may also be cancelled from another thread by setting AbortCurrent to 1LastErrorHtml
my $strVal = $bz2->LastErrorHtml;
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
my $strVal = $bz2->LastErrorText;
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
my $strVal = $bz2->LastErrorXml;
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastMethodSuccess
my $boolVal = $bz2->LastMethodSuccess;
$bz2->LastMethodSuccess($boolVal);
Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
VerboseLogging
my $boolVal = $bz2->VerboseLogging;
$bz2->VerboseLogging($boolVal);
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
my $strVal = $bz2->Version;
Methods
CompressBd
Compresses the current contents of $bd in place. On success, the BinData no longer contains the original bytes; it contains the complete standard BZip2 stream that may be saved with a .bz2 extension.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
CompressFile
# $toPath is a string
# $success is true or false
my $success = $bz2->CompressFile($inFilename, $toPath);
Reads the file at $inFilename and writes its compressed bytes as a standard BZip2 stream to the file at $toPath. The output is conventionally given a .bz2 extension.
Both arguments must identify files, not directories. They may be absolute or relative paths, for example data/report.txt and data/report.txt.bz2.
.bz2 file represents one compressed byte stream. It does not store the original filename, directory path, timestamps, permissions, or multiple archive entries. Formats such as .tar.bz2 first combine files in a TAR archive and then compress that TAR stream with BZip2.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
UncompressBd
Decompresses the BZip2 stream currently contained in $bd in place. On success, the BinData is replaced with the original uncompressed bytes.
$bd must contain a complete, valid BZip2 stream, such as the bytes of a .bz2 file or the output of CompressBd. This method operates on binary data and does not perform character-set conversion.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
UncompressFile
# $toPath is a string
# $success is true or false
my $success = $bz2->UncompressFile($inFilename, $toPath);
Reads the BZip2 stream from the file at $inFilename, decompresses it, and writes the original uncompressed bytes to the file at $toPath.
Both arguments must identify files, not directories. Chilkat does not derive the destination name from the .bz2 filename because the BZip2 stream does not contain the original filename.
.bz2 file normally contains a single compressed byte stream rather than a collection of named files.Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, Chilkat2::Bz2 reports progress to handlers installed with on, which takes Event => CODE pairs (closures, so a handler can use the variables around it):
$bz2->on(
PercentDone => sub { my ($pctDone) = @_; print "$pctDone%\n"; return 0 }, # a true return aborts
ProgressInfo => sub { my ($name, $value) = @_; print "$name: $value\n" },
);
$bz2->HeartbeatMs(250); # the AbortCheck handler is called 4 times per secondInstalls the handlers given, replacing those installed before for the same events; undef instead of a CODE reference removes one, and $bz2->on() with no arguments returns the installed handlers as a list of pairs. The event names are checked: a misspelled one croaks, and nothing is installed.
The AbortCheck handler is called at the interval set by the HeartbeatMs property (0, the default, disables it); PercentDone is called when an operation's completion percentage is known; ProgressInfo delivers named progress values. A true return from the AbortCheck or PercentDone handler aborts the running method, which then fails in the usual way (false or undef, or a Chilkat2::Error under RaiseError).
Handlers run during the method call, on the thread that called it. Inside a handler, other objects may be used, but calling a method of the same object (or its on) croaks. A die in a handler aborts the running method and is re-thrown from the method call; the object remains usable. A handler that uses $bz2 itself makes a reference cycle: weaken the captured copy (Scalar::Util) or remove the handler when done.
AbortCheck
$bz2->on(AbortCheck => sub { ... });
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
my $deadline = time() + 30; # give up after 30 seconds
$bz2->HeartbeatMs(250); # call the handler 4 times per second
$bz2->on(AbortCheck => sub { return time() > $deadline });PercentDone
$bz2->on(PercentDone => sub { ... });
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to 1. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
$bz2->on(PercentDone => sub {
my ($pctDone) = @_; # 0 to 100
print "Percent done: $pctDone\n";
return 0; # return a true value to abort the method in progress
});ProgressInfo
$bz2->on(ProgressInfo => sub { ... });
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
$bz2->on(ProgressInfo => sub {
my ($name, $value) = @_;
print "$name: $value\n";
});