feat(get): consolidate GET performance optimization (#3972)

* feat(get): consolidate GET performance optimization

Consolidated implementation of all GET performance optimizations into
a single, well-organized commit replacing the previous patch-on-patch
approach.

## Changes

### Configuration (set_disk/mod.rs)
- Consolidated all GET optimization flags into a single organized section
- Enabled by default: codec streaming, metadata early-stop, page cache reclaim
- Added codec streaming multipart flag (default: disabled)
- Added version-aware early-stop flag (default: disabled)
- Added adaptive duplex buffer sizing based on object size
- All flags use OnceLock caching with rollout percentage support

### Metadata Early-Stop (set_disk/read.rs)
- Delete marker early-stop when quorum agrees
- Version-aware early-stop for versioned GET requests
- MetadataQuorumAccumulator enhanced with:
  - delete_marker_votes tracking
  - requested_version_id and matching_version_votes tracking
  - version_early_stop_decision() method
- 6 new tests for version early-stop scenarios

### Codec Streaming (erasure/coding/decode_reader.rs)
- DualInFlight (2-stripe lookahead) enabled by default

### Decode Pipeline (erasure/coding/decode.rs)
- Stripe prefetch count configuration
- Bitrot-decode overlap configuration

### Disk Layer (disk/local.rs)
- O_DIRECT read configuration constants (preparation)

### Metrics (io-metrics/lib.rs)
- BytesPool acquisition/return metrics
- Metadata phase duration with early-stop label
- Total duration with reader_path label

### Diagnostics (diagnostics/)
- Early-stop reason constants
- Pool tier/outcome label constants

### Observability (.docker/observability/)
- 3 Grafana dashboards for GET optimization monitoring
- Prometheus alert rules (6 alerts: 3 critical, 3 warning)
- Updated README.md and README_ZH.md with usage docs

### Config (config/src/constants/runtime.rs)
- Page cache reclaim read enabled by default

## Environment Variables

| Variable | Default | Description |
|----------|---------|-------------|
| RUSTFS_GET_CODEC_STREAMING_ENABLE | true | Codec streaming base flag |
| RUSTFS_GET_CODEC_STREAMING_ROLLOUT_PCT | 100 | Codec streaming rollout % |
| RUSTFS_GET_CODEC_STREAMING_MULTIPART_ENABLE | false | Multipart codec streaming |
| RUSTFS_GET_METADATA_EARLY_STOP_ENABLE | true | Early-stop base flag |
| RUSTFS_GET_METADATA_EARLY_STOP_ROLLOUT_PCT | 100 | Early-stop rollout % |
| RUSTFS_GET_METADATA_VERSION_EARLY_STOP_ENABLE | false | Version-aware early-stop |
| RUSTFS_OBJECT_FILE_CACHE_RECLAIM_READ_ENABLE | true | Page cache reclaim |
| RUSTFS_OBJECT_DIRECT_IO_READ_ENABLE | false | O_DIRECT (preparation) |
| RUSTFS_GET_DECODE_STRIPE_PREFETCH_COUNT | 1 | Stripe prefetch |
| RUSTFS_GET_BITROT_DECODE_OVERLAP_ENABLE | false | Bitrot-decode overlap |
| RUSTFS_GET_CODEC_STREAMING_MAX_INFLIGHT | 2 | DualInFlight stripes |

## Rollback

All optimizations can be disabled via environment variables:
RUSTFS_GET_CODEC_STREAMING_ENABLE=false
RUSTFS_GET_METADATA_EARLY_STOP_ENABLE=false
RUSTFS_OBJECT_FILE_CACHE_RECLAIM_READ_ENABLE=false

Co-Authored-By: heihutu <heihutu@gmail.com>

* test(get): add stress test scripts for GET optimization validation

- quick-validate-get-optimization.sh: Quick 5-minute validation
- stress-test-get-optimization.sh: Full 30+ minute stress test
- README-stress-test.md: Usage documentation

Co-Authored-By: heihutu <heihutu@gmail.com>

* test(ecstore): align file cache reclaim defaults

* chore(deps): update redis and erasure codec

* test(ecstore): align decode fill policy default

* test(ecstore): align metadata early-stop default

* fix(ecstore): keep metadata early stop opt-in

---------

Co-authored-by: heihutu <heihutu@gmail.com>

crates/heal/tests/heal_integration_test.rs

@@ -22,7 +22,7 @@ use rustfs_heal::heal::{
 use serial_test::serial;
 use std::{
     path::{Path, PathBuf},
-    sync::{Arc, Once, OnceLock},
+    sync::{Arc, Once},
     time::Duration,
 };
 use tokio::fs;
@@ -59,7 +59,6 @@ async fn wait_for_path_exists(path: &Path, timeout: Duration, interval: Duration
     }
 }
 
-static GLOBAL_ENV: OnceLock<(Vec<PathBuf>, Arc<ECStore>, Arc<ECStoreHealStorage>)> = OnceLock::new();
 static INIT: Once = Once::new();
 
 pub fn init_tracing() {
@@ -76,11 +75,6 @@ pub fn init_tracing() {
 async fn setup_test_env() -> (Vec<PathBuf>, Arc<ECStore>, Arc<ECStoreHealStorage>) {
     init_tracing();
 
-    // Fast path: already initialized, just clone and return
-    if let Some((paths, ecstore, heal_storage)) = GLOBAL_ENV.get() {
-        return (paths.clone(), ecstore.clone(), heal_storage.clone());
-    }
-
     // create temp dir as 4 disks with unique base dir
     let test_base_dir = format!("/tmp/rustfs_heal_heal_test_{}", uuid::Uuid::new_v4());
     let temp_dir = std::path::PathBuf::from(&test_base_dir);
@@ -126,9 +120,9 @@ async fn setup_test_env() -> (Vec<PathBuf>, Arc<ECStore>, Arc<ECStoreHealStorage
     // format disks (only first time)
     init_local_disks(endpoint_pools.clone()).await.unwrap();
 
-    // create ECStore with dynamic port 0 (let OS assign) or fixed 9001 if free
-    let port = 9001; // for simplicity
-    let server_addr: std::net::SocketAddr = format!("127.0.0.1:{port}").parse().unwrap();
+    // Use port 0 so nextest can run this integration binary in parallel
+    // with other ECStore-backed tests without sharing a fixed peer port.
+    let server_addr: std::net::SocketAddr = "127.0.0.1:0".parse().unwrap();
     let ecstore = ECStore::new(server_addr, endpoint_pools, CancellationToken::new())
         .await
         .unwrap();
@@ -147,9 +141,6 @@ async fn setup_test_env() -> (Vec<PathBuf>, Arc<ECStore>, Arc<ECStoreHealStorage
     // Create heal storage layer
     let heal_storage = Arc::new(ECStoreHealStorage::new(ecstore.clone()));
 
-    // Store in global once lock
-    let _ = GLOBAL_ENV.set((disk_paths.clone(), ecstore.clone(), heal_storage.clone()));
-
     (disk_paths, ecstore, heal_storage)
 }