rollup merge of #16846 : treeman/debug-doc
This commit is contained in:
Alex Crichton
commit
daefa70f99
|
|
@ -8,120 +8,154 @@
|
|||
// option. This file may not be copied, modified, or distributed
|
||||
// except according to those terms.
|
||||
|
||||
/*!
|
||||
|
||||
Utilities for program-wide and customizable logging
|
||||
|
||||
## Example
|
||||
|
||||
```
|
||||
#![feature(phase)]
|
||||
#[phase(plugin, link)] extern crate log;
|
||||
|
||||
fn main() {
|
||||
debug!("this is a debug {}", "message");
|
||||
error!("this is printed by default");
|
||||
|
||||
if log_enabled!(log::INFO) {
|
||||
let x = 3i * 4i; // expensive computation
|
||||
info!("the answer was: {}", x);
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
## Logging Macros
|
||||
|
||||
There are five macros that the logging subsystem uses:
|
||||
|
||||
* `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
|
||||
related `format!` arguments
|
||||
* `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
|
||||
* `info!(...)` - a macro hard-wired to the log level of `INFO`
|
||||
* `warn!(...)` - a macro hard-wired to the log level of `WARN`
|
||||
* `error!(...)` - a macro hard-wired to the log level of `ERROR`
|
||||
|
||||
All of these macros use the same style of syntax as the `format!` syntax
|
||||
extension. Details about the syntax can be found in the documentation of
|
||||
`std::fmt` along with the Rust tutorial/manual.
|
||||
|
||||
If you want to check at runtime if a given logging level is enabled (e.g. if the
|
||||
information you would want to log is expensive to produce), you can use the
|
||||
following macro:
|
||||
|
||||
* `log_enabled!(level)` - returns true if logging of the given level is enabled
|
||||
|
||||
## Enabling logging
|
||||
|
||||
Log levels are controlled on a per-module basis, and by default all logging is
|
||||
disabled except for `error!` (a log level of 1). Logging is controlled via the
|
||||
`RUST_LOG` environment variable. The value of this environment variable is a
|
||||
comma-separated list of logging directives. A logging directive is of the form:
|
||||
|
||||
```text
|
||||
path::to::module=log_level
|
||||
```
|
||||
|
||||
The path to the module is rooted in the name of the crate it was compiled for,
|
||||
so if your program is contained in a file `hello.rs`, for example, to turn on
|
||||
logging for this file you would use a value of `RUST_LOG=hello`.
|
||||
Furthermore, this path is a prefix-search, so all modules nested in the
|
||||
specified module will also have logging enabled.
|
||||
|
||||
The actual `log_level` is optional to specify. If omitted, all logging will be
|
||||
enabled. If specified, the it must be either a numeric in the range of 1-255, or
|
||||
it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
|
||||
is specified, then all logging less than or equal to that numeral is enabled.
|
||||
For example, if logging level 3 is active, error, warn, and info logs will be
|
||||
printed, but debug will be omitted.
|
||||
|
||||
As the log level for a module is optional, the module to enable logging for is
|
||||
also optional. If only a `log_level` is provided, then the global log level for
|
||||
all modules is set to this value.
|
||||
|
||||
Some examples of valid values of `RUST_LOG` are:
|
||||
|
||||
* `hello` turns on all logging for the 'hello' module
|
||||
* `info` turns on all info logging
|
||||
* `hello=debug` turns on debug logging for 'hello'
|
||||
* `hello=3` turns on info logging for 'hello'
|
||||
* `hello,std::option` turns on hello, and std's option logging
|
||||
* `error,hello=warn` turn on global error logging and also warn for hello
|
||||
|
||||
## Filtering results
|
||||
|
||||
A RUST_LOG directive may include a regex filter. The syntax is to append `/`
|
||||
followed by a regex. Each message is checked against the regex, and is only
|
||||
logged if it matches. Note that the matching is done after formatting the log
|
||||
string but before adding any logging meta-data. There is a single filter for all
|
||||
modules.
|
||||
|
||||
Some examples:
|
||||
|
||||
* `hello/foo` turns on all logging for the 'hello' module where the log message
|
||||
includes 'foo'.
|
||||
* `info/f.o` turns on all info logging where the log message includes 'foo',
|
||||
'f1o', 'fao', etc.
|
||||
* `hello=debug/foo*foo` turns on debug logging for 'hello' where the the log
|
||||
message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc.
|
||||
* `error,hello=warn/[0-9] scopes` turn on global error logging and also warn for
|
||||
hello. In both cases the log message must include a single digit number
|
||||
followed by 'scopes'
|
||||
|
||||
## Performance and Side Effects
|
||||
|
||||
Each of these macros will expand to code similar to:
|
||||
|
||||
```rust,ignore
|
||||
if log_level <= my_module_log_level() {
|
||||
::log::log(log_level, format!(...));
|
||||
}
|
||||
```
|
||||
|
||||
What this means is that each of these macros are very cheap at runtime if
|
||||
they're turned off (just a load and an integer comparison). This also means that
|
||||
if logging is disabled, none of the components of the log will be executed.
|
||||
|
||||
*/
|
||||
//! Utilities for program-wide and customizable logging
|
||||
//!
|
||||
//! ## Example
|
||||
//!
|
||||
//! ```
|
||||
//! #![feature(phase)]
|
||||
//! #[phase(plugin, link)] extern crate log;
|
||||
//!
|
||||
//! fn main() {
|
||||
//! debug!("this is a debug {}", "message");
|
||||
//! error!("this is printed by default");
|
||||
//!
|
||||
//! if log_enabled!(log::INFO) {
|
||||
//! let x = 3i * 4i; // expensive computation
|
||||
//! info!("the answer was: {}", x);
|
||||
//! }
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! Assumes the binary is `main`:
|
||||
//!
|
||||
//! ```{.bash}
|
||||
//! $ RUST_LOG=error ./main
|
||||
//! ERROR:main: this is printed by default
|
||||
//! ```
|
||||
//!
|
||||
//! ```{.bash}
|
||||
//! $ RUST_LOG=info ./main
|
||||
//! ERROR:main: this is printed by default
|
||||
//! INFO:main: the answer was: 12
|
||||
//! ```
|
||||
//!
|
||||
//! ```{.bash}
|
||||
//! $ RUST_LOG=debug ./main
|
||||
//! DEBUG:main: this is a debug message
|
||||
//! ERROR:main: this is printed by default
|
||||
//! INFO:main: the answer was: 12
|
||||
//! ```
|
||||
//!
|
||||
//! You can also set the log level on a per module basis:
|
||||
//!
|
||||
//! ```{.bash}
|
||||
//! $ RUST_LOG=main=info ./main
|
||||
//! ERROR:main: this is printed by default
|
||||
//! INFO:main: the answer was: 12
|
||||
//! ```
|
||||
//!
|
||||
//! And enable all logging:
|
||||
//!
|
||||
//! ```{.bash}
|
||||
//! $ RUST_LOG=main ./main
|
||||
//! DEBUG:main: this is a debug message
|
||||
//! ERROR:main: this is printed by default
|
||||
//! INFO:main: the answer was: 12
|
||||
//! ```
|
||||
//!
|
||||
//!
|
||||
//! ## Logging Macros
|
||||
//!
|
||||
//! There are five macros that the logging subsystem uses:
|
||||
//!
|
||||
//! * `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
|
||||
//! related `format!` arguments
|
||||
//! * `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
|
||||
//! * `info!(...)` - a macro hard-wired to the log level of `INFO`
|
||||
//! * `warn!(...)` - a macro hard-wired to the log level of `WARN`
|
||||
//! * `error!(...)` - a macro hard-wired to the log level of `ERROR`
|
||||
//!
|
||||
//! All of these macros use the same style of syntax as the `format!` syntax
|
||||
//! extension. Details about the syntax can be found in the documentation of
|
||||
//! `std::fmt` along with the Rust tutorial/manual.
|
||||
//!
|
||||
//! If you want to check at runtime if a given logging level is enabled (e.g. if the
|
||||
//! information you would want to log is expensive to produce), you can use the
|
||||
//! following macro:
|
||||
//!
|
||||
//! * `log_enabled!(level)` - returns true if logging of the given level is enabled
|
||||
//!
|
||||
//! ## Enabling logging
|
||||
//!
|
||||
//! Log levels are controlled on a per-module basis, and by default all logging is
|
||||
//! disabled except for `error!` (a log level of 1). Logging is controlled via the
|
||||
//! `RUST_LOG` environment variable. The value of this environment variable is a
|
||||
//! comma-separated list of logging directives. A logging directive is of the form:
|
||||
//!
|
||||
//! ```text
|
||||
//! path::to::module=log_level
|
||||
//! ```
|
||||
//!
|
||||
//! The path to the module is rooted in the name of the crate it was compiled for,
|
||||
//! so if your program is contained in a file `hello.rs`, for example, to turn on
|
||||
//! logging for this file you would use a value of `RUST_LOG=hello`.
|
||||
//! Furthermore, this path is a prefix-search, so all modules nested in the
|
||||
//! specified module will also have logging enabled.
|
||||
//!
|
||||
//! The actual `log_level` is optional to specify. If omitted, all logging will be
|
||||
//! enabled. If specified, the it must be either a numeric in the range of 1-255, or
|
||||
//! it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
|
||||
//! is specified, then all logging less than or equal to that numeral is enabled.
|
||||
//! For example, if logging level 3 is active, error, warn, and info logs will be
|
||||
//! printed, but debug will be omitted.
|
||||
//!
|
||||
//! As the log level for a module is optional, the module to enable logging for is
|
||||
//! also optional. If only a `log_level` is provided, then the global log level for
|
||||
//! all modules is set to this value.
|
||||
//!
|
||||
//! Some examples of valid values of `RUST_LOG` are:
|
||||
//!
|
||||
//! * `hello` turns on all logging for the 'hello' module
|
||||
//! * `info` turns on all info logging
|
||||
//! * `hello=debug` turns on debug logging for 'hello'
|
||||
//! * `hello=3` turns on info logging for 'hello'
|
||||
//! * `hello,std::option` turns on hello, and std's option logging
|
||||
//! * `error,hello=warn` turn on global error logging and also warn for hello
|
||||
//!
|
||||
//! ## Filtering results
|
||||
//!
|
||||
//! A RUST_LOG directive may include a regex filter. The syntax is to append `/`
|
||||
//! followed by a regex. Each message is checked against the regex, and is only
|
||||
//! logged if it matches. Note that the matching is done after formatting the log
|
||||
//! string but before adding any logging meta-data. There is a single filter for all
|
||||
//! modules.
|
||||
//!
|
||||
//! Some examples:
|
||||
//!
|
||||
//! * `hello/foo` turns on all logging for the 'hello' module where the log message
|
||||
//! includes 'foo'.
|
||||
//! * `info/f.o` turns on all info logging where the log message includes 'foo',
|
||||
//! 'f1o', 'fao', etc.
|
||||
//! * `hello=debug/foo*foo` turns on debug logging for 'hello' where the the log
|
||||
//! message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc.
|
||||
//! * `error,hello=warn/[0-9] scopes` turn on global error logging and also warn for
|
||||
//! hello. In both cases the log message must include a single digit number
|
||||
//! followed by 'scopes'
|
||||
//!
|
||||
//! ## Performance and Side Effects
|
||||
//!
|
||||
//! Each of these macros will expand to code similar to:
|
||||
//!
|
||||
//! ```rust,ignore
|
||||
//! if log_level <= my_module_log_level() {
|
||||
//! ::log::log(log_level, format!(...));
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! What this means is that each of these macros are very cheap at runtime if
|
||||
//! they're turned off (just a load and an integer comparison). This also means that
|
||||
//! if logging is disabled, none of the components of the log will be executed.
|
||||
|
||||
#![crate_name = "log"]
|
||||
#![experimental]
|
||||
|
|
|
|||
|
|
@ -24,11 +24,31 @@
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// log!(log::DEBUG, "this is a debug message");
|
||||
/// log!(log::WARN, "this is a warning {}", "message");
|
||||
/// log!(6, "this is a custom logging level: {level}", level=6u);
|
||||
/// # }
|
||||
/// fn main() {
|
||||
/// log!(log::WARN, "this is a warning {}", "message");
|
||||
/// log!(log::DEBUG, "this is a debug message");
|
||||
/// log!(6, "this is a custom logging level: {level}", level=6u);
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=warn ./main
|
||||
/// WARN:main: this is a warning message
|
||||
/// ```
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=debug ./main
|
||||
/// DEBUG:main: this is a debug message
|
||||
/// WARN:main: this is a warning message
|
||||
/// ```
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=6 ./main
|
||||
/// DEBUG:main: this is a debug message
|
||||
/// WARN:main: this is a warning message
|
||||
/// 6:main: this is a custom logging level: 6
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! log(
|
||||
|
|
@ -53,11 +73,19 @@ macro_rules! log(
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// # let error = 3u;
|
||||
/// error!("the build has failed with error code: {}", error);
|
||||
/// # }
|
||||
/// fn main() {
|
||||
/// let error = 3u;
|
||||
/// error!("the build has failed with error code: {}", error);
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=error ./main
|
||||
/// ERROR:main: the build has failed with error code: 3
|
||||
/// ```
|
||||
///
|
||||
#[macro_export]
|
||||
macro_rules! error(
|
||||
($($arg:tt)*) => (log!(::log::ERROR, $($arg)*))
|
||||
|
|
@ -71,10 +99,17 @@ macro_rules! error(
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// # let code = 3u;
|
||||
/// warn!("you may like to know that a process exited with: {}", code);
|
||||
/// # }
|
||||
/// fn main() {
|
||||
/// let code = 3u;
|
||||
/// warn!("you may like to know that a process exited with: {}", code);
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=warn ./main
|
||||
/// WARN:main: you may like to know that a process exited with: 3
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! warn(
|
||||
|
|
@ -89,10 +124,17 @@ macro_rules! warn(
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// # let ret = 3i;
|
||||
/// info!("this function is about to return: {}", ret);
|
||||
/// # }
|
||||
/// fn main() {
|
||||
/// let ret = 3i;
|
||||
/// info!("this function is about to return: {}", ret);
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=info ./main
|
||||
/// INFO:main: this function is about to return: 3
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! info(
|
||||
|
|
@ -109,9 +151,16 @@ macro_rules! info(
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// debug!("x = {x}, y = {y}", x=10i, y=20i);
|
||||
/// # }
|
||||
/// fn main() {
|
||||
/// debug!("x = {x}, y = {y}", x=10i, y=20i);
|
||||
/// }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=debug ./main
|
||||
/// DEBUG:main: x = 10, y = 20
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! debug(
|
||||
|
|
@ -126,14 +175,26 @@ macro_rules! debug(
|
|||
/// #![feature(phase)]
|
||||
/// #[phase(plugin, link)] extern crate log;
|
||||
///
|
||||
/// # fn main() {
|
||||
/// # struct Point { x: int, y: int }
|
||||
/// # fn some_expensive_computation() -> Point { Point { x: 1, y: 2 } }
|
||||
/// if log_enabled!(log::DEBUG) {
|
||||
/// let x = some_expensive_computation();
|
||||
/// debug!("x.x = {}, x.y = {}", x.x, x.y);
|
||||
/// struct Point { x: int, y: int }
|
||||
/// fn some_expensive_computation() -> Point { Point { x: 1, y: 2 } }
|
||||
///
|
||||
/// fn main() {
|
||||
/// if log_enabled!(log::DEBUG) {
|
||||
/// let x = some_expensive_computation();
|
||||
/// debug!("x.x = {}, x.y = {}", x.x, x.y);
|
||||
/// }
|
||||
/// }
|
||||
/// # }
|
||||
/// ```
|
||||
///
|
||||
/// Assumes the binary is `main`:
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=error ./main
|
||||
/// ```
|
||||
///
|
||||
/// ```{.bash}
|
||||
/// $ RUST_LOG=debug ./main
|
||||
/// DEBUG:main: x.x = 1, x.y = 2
|
||||
/// ```
|
||||
#[macro_export]
|
||||
macro_rules! log_enabled(
|
||||
|
|
|
|||
Loading…
Reference in New Issue