tracing-core/src/context.rs

use crate::{Span, TracingSpan};

/// Context represents the context of a tracing process.
/// All new span belonging to this tracing context should be created through this context.
pub trait Context<'a> {
    /// Fetch the next id for new span
    fn next_span_id(&mut self) -> i32;
    fn create_entry_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span>;
    fn create_exit_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span>;
    fn create_local_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span>;
}

pub struct TracingContext {
    /// Span id sequence. Indicate the number of created spans.
    next_seq: i32,
}

impl TracingContext {
    /// Create a new instance
    pub fn new() -> Self {
        TracingContext {
            next_seq: -1
        }
    }
}

/// Default implementation of Context
impl<'a> Context<'a> for TracingContext {
    /// Fetch the next id for new span
    fn next_span_id(&mut self) -> i32 {
        self.next_seq = self.next_seq + 1;
        self.next_seq
    }

    fn create_entry_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span> {
        TracingSpan::new_entry_span(operation_name, self, parent)
    }

    fn create_exit_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span> {
        TracingSpan::new_exit_span(operation_name,  self, parent)
    }

    fn create_local_span(&mut self, operation_name: String, parent: Option<&dyn Span>) -> Box<dyn Span> {
        TracingSpan::new_local_span(operation_name,  self, parent)
    }
}