OutboundCache (Javadocs [I2P+ 2.13.0+]

java.lang.Object
- net.i2p.router.message.OutboundCache

```
public class OutboundCache
extends Object
```
Helper cache manager for outbound message optimization in OCMOSJ.
This class maintains several caches to optimize outbound message routing and delivery:
- LeaseSet cache - minimizes overhead by reusing our own LeaseSet.
- Lease cache - persists sending to the same lease to reduce out-of-order delivery.
- Tunnel caches - caches outbound tunnels per destination to stabilize delivery paths.
- Last reply request cache - ensures periodic replies to detect failed tunnels.
- Multihomed cache - tracks LeaseSets for multihomed routers.
All caches use ConcurrentHashMap with tuned initial capacity, load factor, and concurrency level to allow safe concurrent access and high throughput with low contention. Tunnel caches have been converted from HashMaps with explicit synchronization to ConcurrentHashMaps for consistent concurrency management without external locking.
Cache cleaning occurs periodically with a configurable interval, removing expired entries to balance memory use and cache freshness.

Nested Class Summary
Nested Classes
Modifier and Type Class and Description
(package private) static class OutboundCache.HashPair
Composite key for caches, combining source and destination Hashes.

Nested Classes
Modifier and Type	Class and Description
`(package private) static class`	`OutboundCache.HashPair` Composite key for caches, combining source and destination Hashes.

Field Summary

Fields
Modifier and Type	Field and Description
`(package private) ConcurrentHashMap<OutboundCache.HashPair,TunnelInfo>`	`backloggedTunnelCache` Cache for backlogged tunnels per source-destination pair.
`(package private) ConcurrentHashMap<OutboundCache.HashPair,Long>`	`lastReplyRequestCache` Cache to track the last reply request time per source-destination pair.
`(package private) ConcurrentHashMap<OutboundCache.HashPair,Lease>`	`leaseCache` Lease cache keyed by source-destination pairs.
`(package private) ConcurrentHashMap<OutboundCache.HashPair,LeaseSet>`	`leaseSetCache` LeaseSet cache keyed by source-destination pairs.
`ConcurrentHashMap<Hash,LeaseSet>`	`multihomedCache` Cache for LeaseSets associated with multihomed routers or hosted destinations.
`(package private) ConcurrentHashMap<OutboundCache.HashPair,TunnelInfo>`	`tunnelCache` Cache for outbound tunnels per source-destination pair.
`(package private) ConcurrentHashMap<OutboundCache.HashPair,Long>`	`tunnelStartTime` Tracks when each tunnel was first selected for a source-destination pair, to prevent rapid tunnel switching that causes out-of-order delivery and unnecessary NACKs in the streaming layer.

Constructor Summary
Constructors
Constructor and Description
OutboundCache(RouterContext ctx)
Creates an OutboundCache instance and schedules periodic cache cleanup.

Constructors
Constructor and Description
`OutboundCache(RouterContext ctx)` Creates an OutboundCache instance and schedules periodic cache cleanup.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clearAllCaches()` Clears all caches managed by this instance.
`(package private) void`	`clearCaches(OutboundCache.HashPair hashPair, Lease lease, TunnelInfo inTunnel, TunnelInfo outTunnel)` Clears cache entries related to the provided key and elements upon failure, allowing retries with fresh associations.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - backloggedTunnelCache
```
final ConcurrentHashMap<OutboundCache.HashPair,TunnelInfo> backloggedTunnelCache
```
    Cache for backlogged tunnels per source-destination pair. Also uses ConcurrentHashMap for consistency and concurrency.
  - lastReplyRequestCache
```
final ConcurrentHashMap<OutboundCache.HashPair,Long> lastReplyRequestCache
```
    Cache to track the last reply request time per source-destination pair. Used to detect and recover from failed tunnels.
  - leaseCache
```
final ConcurrentHashMap<OutboundCache.HashPair,Lease> leaseCache
```
    Lease cache keyed by source-destination pairs. Ensures persistent use of the same inbound lease to minimize out-of-order delivery.
  - leaseSetCache
```
final ConcurrentHashMap<OutboundCache.HashPair,LeaseSet> leaseSetCache
```
    LeaseSet cache keyed by source-destination pairs. Controls when to bundle our own LeaseSet to reduce overhead on repeated communications.
  - multihomedCache
```
public final ConcurrentHashMap<Hash,LeaseSet> multihomedCache
```
    Cache for LeaseSets associated with multihomed routers or hosted destinations.
  - tunnelCache
```
final ConcurrentHashMap<OutboundCache.HashPair,TunnelInfo> tunnelCache
```
    Cache for outbound tunnels per source-destination pair. Maintains consistent outbound tunnel usage to optimize streaming performance. Uses ConcurrentHashMap for thread safety and high concurrency.
  - tunnelStartTime
```
final ConcurrentHashMap<OutboundCache.HashPair,Long> tunnelStartTime
```
    Tracks when each tunnel was first selected for a source-destination pair, to prevent rapid tunnel switching that causes out-of-order delivery and unnecessary NACKs in the streaming layer.
- Constructor Detail
  - OutboundCache
```
public OutboundCache(RouterContext ctx)
```
    Creates an OutboundCache instance and schedules periodic cache cleanup.
    Parameters:
    ctx - the router context providing environment and utilities.
- Method Detail
  - clearAllCaches
```
public void clearAllCaches()
```
    Clears all caches managed by this instance. Use cautiously as this impacts performance temporarily.
  - clearCaches
```
void clearCaches(OutboundCache.HashPair hashPair,
                 Lease lease,
                 TunnelInfo inTunnel,
                 TunnelInfo outTunnel)
```
    Clears cache entries related to the provided key and elements upon failure, allowing retries with fresh associations.
    Parameters:
    hashPair - the source-destination key for caches.
    lease - lease to clear from leaseCache, may be null.
    inTunnel - inbound tunnel to check for leaseSetCache invalidation, may be null.
    outTunnel - outbound tunnel to clear from tunnel caches, may be null.

Class OutboundCache

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

backloggedTunnelCache

lastReplyRequestCache

leaseCache

leaseSetCache

multihomedCache

tunnelCache

tunnelStartTime

Constructor Detail

OutboundCache

Method Detail

clearAllCaches

clearCaches