Bz2 Rust Reference Documentation
Bz2
Current Version: 11.6.1
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
// Cargo.toml:
// [dependencies]
// chilkat = "11.6"
use chilkat::Bz2;
// Once per process, before any other Chilkat call:
chilkat::unlock_bundle("Anything for 30-day trial")?; // shorthand for Global::new().unlock_bundle(..)
let bz2 = Bz2::new();
// ... the native object is freed when `bz2` goes out of scope.Creates the underlying native Chilkat object (Bz2 also implements Default). Every method takes &self, so the object never needs to be declared mut. A Bz2 is Send but not Sync: it may be moved to another thread, but a reference to it cannot be shared between threads at the same time.
The native object is freed when the Bz2 is dropped — when it goes out of scope, or explicitly with drop(bz2). There is no Dispose method to call.
Errors
Methods that can fail return chilkat::Result<T>, which is Result<T, chilkat::Error>: a method whose only outcome is success or failure returns Result<()>, a method producing a string or an object returns Result<String> or Result<Bz2>. The error carries the object's LastErrorText at the time of the failure (Error::last_error_text), the class and method names, and implements std::error::Error, so ? works in any function returning chilkat::Result or a Box<dyn Error>. Properties never fail, and methods that answer a question (has_..., is_..., ...) return a plain bool.
match bz2.some_method(...) {
Ok(value) => println!("{value:?}"),
Err(e) => eprintln!("{}", e.last_error_text()),
}Properties
AbortCurrent
pub fn abort_current(&self) -> bool
pub fn set_abort_current(&self, value: bool)
Set this property to true
A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to false
LastErrorText to determine the final outcome.DebugLogFilePath
pub fn debug_log_file_path(&self) -> String
pub fn set_debug_log_file_path(&self, value: &str)
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
pub fn heartbeat_ms(&self) -> i32
pub fn set_heartbeat_ms(&self, value: i32)
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 trueLastErrorHtml
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
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
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
pub fn last_method_success(&self) -> bool
pub fn set_last_method_success(&self, value: bool)
Indicates the success or failure of the most recent method call: true means success, false 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
pub fn verbose_logging(&self) -> bool
pub fn set_verbose_logging(&self, value: bool)
If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
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 Ok(()) for success, Err(chilkat::Error) for failure.
CompressFile
Reads the file at in_filename and writes its compressed bytes as a standard BZip2 stream to the file at to_path. 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 Ok(()) for success, Err(chilkat::Error) for failure.
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 Ok(()) for success, Err(chilkat::Error) for failure.
UncompressFile
Reads the BZip2 stream from the file at in_filename, decompresses it, and writes the original uncompressed bytes to the file at to_path.
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 Ok(()) for success, Err(chilkat::Error) for failure.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a call, Bz2 raises three events so your application can show progress and offer a way out. Implement the chilkat::EventHandler trait (every method has a do-nothing default, so implement only the events you need) and install it with set_event_handler:
use chilkat::{Bz2, EventHandler};
struct Progress;
impl EventHandler for Progress {
fn percent_done(&mut self, pct: i32) -> bool {
println!("{pct}%");
false // return true to abort the method in progress
}
fn progress_info(&mut self, name: &str, value: &str) {
println!("{name}: {value}");
}
}
let bz2 = Bz2::new();
bz2.set_event_handler(Progress);
bz2.set_heartbeat_ms(250); // raise abort_check 4 times per second during Chilkat callsFor a one-off handler the closure methods avoid writing a type; they may be combined, and each replaces the previously set closure for that one event (installing a closure removes a trait handler set earlier, and vice versa):
bz2.on_percent_done(|pct| { println!("{pct}%"); false });
bz2.on_progress_info(|name, value| println!("{name}: {value}"));Installs handler as the receiver of this object's events, replacing any handler or closures set earlier. The object owns the handler, which must be Send + 'static.
Removes the handler and any closures; events are no longer delivered.
AbortCheck fires at regular intervals controlled by the HeartbeatMs property (0, the default, disables it); PercentDone fires when an operation's completion percentage is known; ProgressInfo delivers named progress values. Returning true from abort_check or percent_done aborts the running method, which then returns Err.
Events fire on the thread that called the method, before that method returns. A panic inside a handler aborts the running method and is re-raised to the caller once the native library has returned, so it never unwinds through C frames. To abort a long operation from another thread, share an Arc<AtomicBool> with an abort_check handler, or set the object's AbortCurrent property to true.
AbortCheck
fn abort_check(&mut self) -> bool
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 (closure form; the EventHandler trait method is equivalent):
bz2.set_heartbeat_ms(250); // call abort_check 4 times per second
let stop = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
let flag = stop.clone();
bz2.on_abort_check(move || flag.load(std::sync::atomic::Ordering::Relaxed));
// ... another thread may now abort the method in progress with stop.store(true, Ordering::Relaxed)PercentDone
fn percent_done(&mut self, pct: i32) -> bool
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 pct_done 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 pct_done 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 true. This will cause the method to terminate and return a failure status or corresponding failure value.
Example (closure form; the EventHandler trait method is equivalent):
bz2.on_percent_done(|pct| {
// pct ranges from 1 to 100.
println!("Percent done: {pct}");
false // return true to abort the method in progress
});ProgressInfo
fn progress_info(&mut self, name: &str, value: &str)
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 (closure form; the EventHandler trait method is equivalent):
bz2.on_progress_info(|name, value| println!("{name}: {value}"));