Module buffer 

Centralized memory management with pressure handling.

When you need to control total memory usage across the database (not just individual allocations), this is what you use. The BufferManager tracks all allocations, monitors memory pressure, and can trigger spilling when you’re running low.

Architecture

┌────────────────────────────────────────────────────────────┐
│                    BufferManager                           │
│  ┌──────────────┬──────────────┬──────────────┬──────────┐ │
│  │ GraphStorage │ IndexBuffers │ Execution    │ Spill    │ │
│  │              │              │ Buffers      │ Staging  │ │
│  └──────────────┴──────────────┴──────────────┴──────────┘ │
│                         │                                  │
│  Pressure Thresholds:   │                                  │
│  < 70%  Normal          │                                  │
│  70-85% Moderate (evict cold)                              │
│  85-95% High (aggressive evict/spill)                      │
│  > 95%  Critical (block allocations)                       │
└────────────────────────────────────────────────────────────┘

Usage

use grafeo_common::memory::buffer::{BufferManager, MemoryRegion};

// Create with default config (75% of system RAM)
let manager = BufferManager::with_defaults();

// Or with specific budget
let manager = BufferManager::with_budget(1024 * 1024 * 100); // 100MB

// Allocate memory
if let Some(grant) = manager.try_allocate(1024, MemoryRegion::ExecutionBuffers) {
    // Use the memory...
    // Memory is automatically released when grant is dropped
}

// Check pressure level
let level = manager.pressure_level();
if level.should_spill() {
    // Trigger spilling for spillable operators
}

Modules

priorities

Standard priority levels for common consumer types.

Structs

BufferManager

The central unified buffer manager.

BufferManagerConfig

Configuration for the buffer manager.

BufferStats

Statistics about buffer manager state.

CompositeGrant

A collection of memory grants that can be managed together.

ConsumerStats

Statistics about a memory consumer.

MemoryGrant

RAII wrapper for memory allocations.

Enums

MemoryRegion

Memory region identifiers for budget partitioning.

PressureLevel

Memory pressure level thresholds.

SpillError

Error type for spilling operations.

Traits

GrantReleaser

Trait for releasing memory grants.

MemoryConsumer

Trait for subsystems that consume managed memory.