1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
// This file is part of Substrate.

// Copyright (C) 2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Substrate tracing primitives and macros.
//!
//! To trace functions or invidual code in Substrate, this crate provides [`within_span`]
//! and [`enter_span`]. See the individual docs for how to use these macros.
//!
//! Note that to allow traces from wasm execution environment there are
//! 2 reserved identifiers for tracing `Field` recording, stored in the consts:
//! `WASM_TARGET_KEY` and `WASM_NAME_KEY` - if you choose to record fields, you
//! must ensure that your identifiers do not clash with either of these.
//!
//! Additionally, we have a const: `WASM_TRACE_IDENTIFIER`, which holds a span name used
//! to signal that the 'actual' span name and target should be retrieved instead from
//! the associated Fields mentioned above.

#![cfg_attr(not(feature = "std"), no_std)]

/// Tracing facilities and helpers.
///
/// This is modeled after the `tracing`/`tracing-core` interface and uses that more or
/// less directly for the native side. Because of certain optimisations the these crates
/// have done, the wasm implementation diverges slightly and is optimised for thtat use
/// case (like being able to cross the wasm/native boundary via scale codecs).
///
/// One of said optimisations is that all macros will yield to a `noop` in non-std unless
/// the `with-tracing` feature is explicitly activated. This allows you to just use the
/// tracing wherever you deem fit and without any performance impact by default. Only if
/// the specific `with-tracing`-feature is activated on this crate will it actually include
/// the tracing code in the non-std environment.
///
/// Because of that optimisation, you should not use the `span!` and `span_*!` macros
/// directly as they yield nothing without the feature present. Instead you should use
/// `enter_span!` and `within_span!` – which would strip away even any parameter conversion
/// you do within the span-definition (and thus optimise your performance). For your
/// convineience you directly specify the `Level` and name of the span or use the full
/// feature set of `span!`/`span_*!` on it:
///
/// # Example
///
/// ```rust
/// sp_tracing::enter_span!(sp_tracing::Level::TRACE, "fn wide span");
/// {
///		sp_tracing::enter_span!(sp_tracing::trace_span!("outer-span"));
///		{
///			sp_tracing::enter_span!(sp_tracing::Level::TRACE, "inner-span");
///			// ..
///		}  // inner span exists here
///	} // outer span exists here
///
/// sp_tracing::within_span! {
///		sp_tracing::debug_span!("debug-span", you_can_pass="any params");
///     1 + 1;
///     // some other complex code
/// } // debug span ends here
///
/// ```
///
///
/// # Setup
///
/// This project only provides the macros and facilities to manage tracing
/// it doesn't implement the tracing subscriber or backend directly – that is
/// up to the developer integrating it into a specific environment. In native
/// this can and must be done through the regular `tracing`-facitilies, please
/// see their documentation for details.
///
/// On the wasm-side we've adopted a similar approach of having a global
/// `TracingSubscriber` that the macros call and that does the actual work
/// of tracking. To provide your tracking, you must implement `TracingSubscriber`
/// and call `set_tracing_subscriber` at the very beginning of your execution –
/// the default subscriber is doing nothing, so any spans or events happening before
/// will not be recorded!
///

mod types;

#[cfg(feature = "std")]
use tracing;

pub use tracing::{
	debug, debug_span, error, error_span, info, info_span, trace, trace_span, warn, warn_span,
	span, event, Level, Span,
};

pub use crate::types::{
	WasmMetadata, WasmEntryAttributes, WasmValuesSet, WasmValue, WasmFields, WasmLevel, WasmFieldName
};


/// Try to init a simple tracing subscriber with log compatibility layer.
/// Ignores any error. Useful for testing.
#[cfg(feature = "std")]
pub fn try_init_simple() {
	let _ = tracing_subscriber::fmt().with_writer(std::io::stderr).try_init();
}

#[cfg(feature = "std")]
pub use crate::types::{
	WASM_NAME_KEY, WASM_TARGET_KEY, WASM_TRACE_IDENTIFIER
};


/// Runs given code within a tracing span, measuring it's execution time.
///
/// If tracing is not enabled, the code is still executed. Pass in level and name or
/// use any valid `sp_tracing::Span`followe by `;` and the code to execute,
///
/// # Example
///
/// ```
/// sp_tracing::within_span! {
///		sp_tracing::Level::TRACE,
///     "test-span";
///     1 + 1;
///     // some other complex code
/// }
///
/// sp_tracing::within_span! {
///		sp_tracing::span!(sp_tracing::Level::WARN, "warn-span", you_can_pass="any params");
///     1 + 1;
///     // some other complex code
/// }
///
/// sp_tracing::within_span! {
///		sp_tracing::debug_span!("debug-span", you_can_pass="any params");
///     1 + 1;
///     // some other complex code
/// }
/// ```
#[cfg(any(feature = "std", feature = "with-tracing"))]
#[macro_export]
macro_rules! within_span {
	(
		$span:expr;
		$( $code:tt )*
	) => {
		$span.in_scope(||
			{
				$( $code )*
			}
		)
	};
	(
		$lvl:expr,
		$name:expr;
		$( $code:tt )*
	) => {
		{
			$crate::within_span!($crate::span!($crate::Level::TRACE, $name); $( $code )*)
		}
	};
}

#[cfg(all(not(feature = "std"), not(feature = "with-tracing")))]
#[macro_export]
macro_rules! within_span {
	(
		$span:stmt;
		$( $code:tt )*
	) => {
		$( $code )*
	};
	(
		$lvl:expr,
		$name:expr;
		$( $code:tt )*
	) => {
		$( $code )*
	};
}


/// Enter a span - noop for `no_std` without `with-tracing`
#[cfg(all(not(feature = "std"), not(feature = "with-tracing")))]
#[macro_export]
macro_rules! enter_span {
	( $lvl:expr, $name:expr ) => ( );
	( $name:expr ) => ( ) // no-op
}

/// Enter a span.
///
/// The span will be valid, until the scope is left. Use either level and name
/// or pass in any valid `sp_tracing::Span` for extended usage. The span will
/// be exited on drop – which is at the end of the block or to the next
/// `enter_span!` calls, as this overwrites the local variable. For nested
/// usage or to ensure the span closes at certain time either put it into a block
/// or use `within_span!`
///
/// # Example
///
/// ```
/// sp_tracing::enter_span!(sp_tracing::Level::TRACE, "test-span");
/// // previous will be dropped here
/// sp_tracing::enter_span!(
/// 	sp_tracing::span!(sp_tracing::Level::DEBUG, "debug-span", params="value"));
/// sp_tracing::enter_span!(sp_tracing::info_span!("info-span",  params="value"));
///
/// {
///		sp_tracing::enter_span!(sp_tracing::Level::TRACE, "outer-span");
///		{
///			sp_tracing::enter_span!(sp_tracing::Level::TRACE, "inner-span");
///			// ..
///		}  // inner span exists here
///	} // outer span exists here
///
/// ```
#[cfg(any(feature = "std", feature = "with-tracing"))]
#[macro_export]
macro_rules! enter_span {
	( $span:expr ) => {
		// Calling this twice in a row will overwrite (and drop) the earlier
		// that is a _documented feature_!
		let __within_span__ = $span;
		let __tracing_guard__ = __within_span__.enter();
	};
	( $lvl:expr, $name:expr ) => {
		$crate::enter_span!($crate::span!($crate::Level::TRACE, $name))
	};
}