Method apply_spsc_pressure

nodedb/src/data/executor/core_loop/pressure.rs:81–145

Adjust SPSC read depth based on worst-case pressure across all engines. Called once per tick. Mutates `spsc_read_depth`, `pressure_suspend_reads`, and `pressure_normal_ticks`.

(&mut self)

    /// Called once per tick. Mutates `spsc_read_depth`, `pressure_suspend_reads`,
    /// and `pressure_normal_ticks`.
    pub fn apply_spsc_pressure(&mut self) {
        let Some(ref governor) = self.governor else {
            return;
        };

        // Worst-case pressure across all engines that have a budget.
        let worst = governor.worst_engine_pressure();

        match worst {
            PressureLevel::Normal | PressureLevel::Warning => {
                self.pressure_normal_ticks = self.pressure_normal_ticks.saturating_add(1);
                if self.pressure_suspend_reads
                    && self.pressure_normal_ticks >= PRESSURE_NORMAL_HYSTERESIS
                {
                    // Emergency cleared — lift suspension first.
                    self.pressure_suspend_reads = false;
                    warn!(
                        core = self.core_id,
                        "pressure cleared — resuming SPSC reads"
                    );
                }
                if self.spsc_read_depth < SPSC_READ_DEPTH_NORMAL
                    && self.pressure_normal_ticks >= PRESSURE_NORMAL_HYSTERESIS
                {
                    self.spsc_read_depth = SPSC_READ_DEPTH_NORMAL;
                    warn!(
                        core = self.core_id,
                        read_depth = self.spsc_read_depth,
                        "pressure normal — restored SPSC read depth"
                    );
                }
            }
            PressureLevel::Critical => {
                self.pressure_normal_ticks = 0;
                if self.pressure_suspend_reads {
                    // Coming down from Emergency: lift suspension, set throttled depth.
                    self.pressure_suspend_reads = false;
                    warn!(
                        core = self.core_id,
                        "pressure Critical — lifting SPSC suspension"
                    );
                }
                let new_depth = (self.spsc_read_depth / 2).max(1);
                if new_depth != self.spsc_read_depth {
                    self.spsc_read_depth = new_depth;
                    warn!(
                        core = self.core_id,
                        read_depth = new_depth,
                        "Critical memory pressure — reduced SPSC read depth"
                    );
                }
            }
            PressureLevel::Emergency => {
                self.pressure_normal_ticks = 0;
                if !self.pressure_suspend_reads {
                    self.pressure_suspend_reads = true;
                    self.spsc_read_depth = 1;
                    warn!(