IntroducerLookupJob (Javadocs [I2P+ 2.13.0+]

java.lang.Object
- net.i2p.router.JobImpl
- - net.i2p.router.networkdb.kademlia.IntroducerLookupJob

All Implemented Interfaces:
Job
```
class IntroducerLookupJob
extends JobImpl
```
Background maintenance job that keeps introducer RouterInfos warm in the local netDb. Unreachable (U-cap) peers publish SSU2 introducers as router hashes (the "ih0".."ih4" options on their SSU/SSU2 addresses). When we need an inbound connection from such a peer - or need to reach one ourselves - EstablishmentManager looks up each introducer RI on demand; if the RI is not cached locally, establishment stalls while the search runs, and IntroductionManager must fall back to ad-hoc direct queries. This job reviews the introducers of known unreachable peers on a slow schedule and issues remote RouterInfo lookups for any introducer missing locally, so hole-punching has its prerequisites ready before a connection is attempted. Lookups are aggressively staggered so floodfills never see a burst: a randomized ~10 minute cycle, at most MAX_LOOKUPS_PER_CYCLE searches per cycle, per-introducer exponential backoff after failures, and a dedup/backoff map shared across cycles. Concurrent duplicate searches of the same key are additionally coalesced by IterativeSearchJob. SSU1 introducers carry no router hash (IP/port/intro-key only) and cannot be resolved by netDB lookup; they are skipped here and handled by the transport's existing IP-based introduction path.

Field Summary
- Fields inherited from class net.i2p.router.JobImpl
  _id

Constructor Summary
Constructors
Constructor and Description
IntroducerLookupJob(RouterContext ctx, FloodfillNetworkDatabaseFacade facade)
Constructor.

Constructors
Constructor and Description
`IntroducerLookupJob(RouterContext ctx, FloodfillNetworkDatabaseFacade facade)` Constructor.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`(package private) static long`	`backoffMillis(int fails)` Retry backoff for an introducer whose last lookup failed `fails` consecutive times: 0 (in flight / find pending) → `MIN_RETRY_MS`; 1+ → `FAIL_BACKOFF_MS` doubling per failure, capped at `MAX_FAIL_BACKOFF_MS`.
`(package private) static boolean`	`canAttempt(long now, long[] state)` Gate for issuing a lookup now: true when never attempted, or when the elapsed time since the last attempt meets the state's backoff.
`(package private) static List<Hash>`	`getIntroducerHashes(Collection<RouterAddress> addresses)` Extract SSU2 introducer router hashes ("ih0".."ih4") from the given addresses.
`String`	`getName()` Descriptive name of the task
`(package private) static boolean`	`isUnreachablePeer(RouterInfo ri)` Whether the peer publishes the unreachable capability ('U'), i.e.
`(package private) static Hash`	`parseIntroducerHash(String b64)` Decode an "ih{i}" option value into a Hash: Base64 of exactly 32 bytes, else null.
`void`	`runJob()` Actually perform the task.

Methods inherited from class net.i2p.router.JobImpl
dropped, getContext, getJobId, getMadeReadyOn, getTiming, madeReady, requeue, toString

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

- Constructor Detail
  - IntroducerLookupJob
```
public IntroducerLookupJob(RouterContext ctx,
                           FloodfillNetworkDatabaseFacade facade)
```
    Constructor. Sets the staggered initial start time.
    Parameters:
    ctx - the router context
    facade - the floodfill network database facade
- Method Detail
  - backoffMillis
```
static long backoffMillis(int fails)
```
    Retry backoff for an introducer whose last lookup failed fails consecutive times: 0 (in flight / find pending) → MIN_RETRY_MS; 1+ → FAIL_BACKOFF_MS doubling per failure, capped at MAX_FAIL_BACKOFF_MS. Pure decision — safe for unit tests.
    Parameters:
    fails - consecutive failed lookup attempts
    Returns:
    the backoff in milliseconds
  - canAttempt
```
static boolean canAttempt(long now,
                          long[] state)
```
    Gate for issuing a lookup now: true when never attempted, or when the elapsed time since the last attempt meets the state's backoff. Pure decision — safe for unit tests.
    Parameters:
    now - current time in milliseconds
    state - {last attempt time, consecutive failures}, or null
    Returns:
    true if a lookup may be attempted
  - getIntroducerHashes
```
static List<Hash> getIntroducerHashes(Collection<RouterAddress> addresses)
```
    Extract SSU2 introducer router hashes ("ih0".."ih4") from the given addresses. An introducer slot exists only if its required relay tag option ("itag{i}") is present; SSU1-only slots (ihost/iport/ikey with no "ih") carry no hash and yield nothing. Duplicates removed. Pure decision — no context access, safe for unit tests.
    Parameters:
    addresses - the peer's transport addresses, may be null or empty
    Returns:
    the introducer hashes, never null
  - getName
```
public String getName()
```
    Description copied from interface: Job
    Descriptive name of the task
    Returns:
    the descriptive name of the task
  - isUnreachablePeer
```
static boolean isUnreachablePeer(RouterInfo ri)
```
    Whether the peer publishes the unreachable capability ('U'), i.e. it is firewalled / cannot accept unsolicited connections and therefore relies on introducers for inbound connectivity.
    Parameters:
    ri - the peer's RouterInfo (non-null)
    Returns:
    true if the capabilities string contains 'U'
  - parseIntroducerHash
```
static Hash parseIntroducerHash(String b64)
```
    Decode an "ih{i}" option value into a Hash: Base64 of exactly 32 bytes, else null. Pure decision — safe for unit tests.
    Parameters:
    b64 - the option value, may be null
    Returns:
    the hash, or null if absent/malformed
  - runJob
```
public void runJob()
```
    Description copied from interface: Job
    Actually perform the task. This call blocks until the Job is complete.

Class IntroducerLookupJob

Field Summary

Fields inherited from class net.i2p.router.JobImpl

Constructor Summary

Method Summary

Methods inherited from class net.i2p.router.JobImpl

Methods inherited from class java.lang.Object

Constructor Detail

IntroducerLookupJob

Method Detail

backoffMillis

canAttempt

getIntroducerHashes

getName

isUnreachablePeer

parseIntroducerHash

runJob