forked from lei.chen/myxce
Rongsong Shen
40c2351578
xcecli_joblist/reslist/workerlist/resval/jobinfo return a non-negative ROW COUNT on success (rc = getreply.nrows), not a 0/status code. They were wrapped in XCECLI_FAILOVER_CALL, which unconditionally classifies the raw return value against fixed constants (E_XCE_* and POSIX errno magnitudes accepted in either sign) — a row count that happens to equal one of those constants (e.g. exactly 111 jobs == ECONNREFUSED) was silently misclassified as a transport failure, forcing a spurious xce_failover_rotate() on every call with that exact count. In /xce-test-ha's arithmetic progression (3 + 3*round) this hit at round 36, burning the retry budget on self-inflicted churn until it coincided with a genuine transient and surfaced a real ECONNRESET to the caller. Add XCECLI_FAILOVER_CALL_COUNT: only enters the retry/classify loop when EXPR's raw result is negative; any non-negative result (0 or a genuine row count of any magnitude) is unconditionally success. Switch the five xce_get-family wrappers to it. Verified via 40-round sequential and 40-round chaotic HA soak past round 36, zero committed-job loss.
322 lines
16 KiB
C
322 lines
16 KiB
C
#if !defined(_CLIENT_INTERNAL_H_)
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#define _CLIENT_INTERNAL_H_ 1
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "client.h"
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#include "mylock.h"
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#include "netio.h"
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#include "request.h"
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#include "xce/client_failover.h" /* xce_fo_action_t */
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#include "xcectx.h"
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/*
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* client_internal.h — private libxce client state shared between client.c and
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* the forthcoming failover helper (client_failover.c, task 1.x).
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*
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* api_ctx_t was previously file-local to client.c. It is moved here so the
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* failover helper can operate on it without exposing it through the public
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* API in client.h.
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*/
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typedef enum {
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API_CTX_INIT = 0,
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API_CTX_RUN,
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API_CTX_DOWN,
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API_CTX_ERR
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} api_ctx_state_t;
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/*
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* xcecli_reconnect_cb (consumer rejoin hook) and its public setter
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* xcecli_set_reconnect_handler() are declared in the public client.h (included
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* above) as of task 4.1. The failover state below carries the registered hook.
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*/
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/*
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* xce_failover_state_t: per-context failover state. Persists across calls so a
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* sticky primary and the retry tunables survive between requests.
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*
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* lock — serializes xcecli_* per ctx (shared-ctx safety)
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* cur_master — index into conf->masters[] (sticky primary)
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* retry — defaults from XCE_RETRY_DEFAULTS unless overridden
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* rejoin_cb — consumer rejoin hook; NULL for pure clients
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* rejoin_arg — opaque argument passed to rejoin_cb
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*/
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typedef struct {
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mylock_t lock;
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int cur_master;
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xce_retry_config_t retry;
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xcecli_reconnect_cb rejoin_cb;
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void* rejoin_arg;
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} xce_failover_state_t;
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typedef struct {
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xce_client_config_t* conf;
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endpoint_t ep;
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xce_ctx_t ctx;
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xce_failover_state_t failover;
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} api_ctx_t;
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/*
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* EndpointRotator (task 2.2) — these operate on the private api_ctx_t, so they
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* live in this internal header rather than the public xce/client_failover.h.
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*
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* xce_failover_next_target(): PURE target-selection (no I/O). If a redirect-
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* address hint is set on ac->ctx, write it out and CONSUME it (one-shot,
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* advisory). Otherwise advance the sticky master cursor (ac->failover.cur_master)
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* to the next configured master in ac->conf, wrapping around. Returns 0,
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* -EINVAL on a NULL/zero argument, or -ENOENT if no masters and no hint.
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* Correctness never depends on the hint.
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*
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* xce_failover_rotate(): close the stale connection on ac->ep and reconnect the
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* SAME endpoint object to the chosen target. Thin wrapper over the selector +
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* endpoint_connect(); the live socket path is exercised by the E2E task.
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*/
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int xce_failover_next_target(api_ctx_t* ac, char* host_out, size_t host_sz,
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uint16_t* port_out);
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int xce_failover_rotate(api_ctx_t* ac);
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/*
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* XcecliRetryLoop / decision helper (task 3.1) — see design.md
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* "Components and Interfaces → xcecli_retry_next".
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*
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* xcecli_retry_t: per-op retry carrier. One instance lives on the caller's
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* stack for the duration of a single xcecli_* op's do/while loop.
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* attempt — number of re-sends so far (0 on the first send).
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* delay_ms — backoff to apply BEFORE the next attempt (0 for RETRY_NOW).
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* rand_seed — per-op rand_r() state for jittered backoff (6.3).
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*/
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typedef struct {
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int attempt;
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int delay_ms;
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unsigned int rand_seed;
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} xcecli_retry_t;
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/*
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* XCECLI_RETRY_INIT(ac): initialise a retry carrier from an api_ctx_t. The seed
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* mixes the ctx pointer so concurrent ops on distinct ctxs jitter independently.
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*/
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#define XCECLI_RETRY_INIT(ac) \
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((xcecli_retry_t){ .attempt = 0, \
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.delay_ms = 0, \
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.rand_seed = (unsigned int)(uintptr_t)(ac) })
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/*
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* xcecli_retry_decide(): the PURE decision core (no I/O, no sleep, no socket,
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* no logging) so it is unit-testable. Given the rc returned by the last xce_*
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* attempt, it:
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* - classifies *rc via xce_failover_classify(*rc, is_write, st->attempt);
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* - on SUCCESS applies the DUP-replay rule (sets *rc = 0) and returns false;
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* - on TERMINAL returns false leaving *rc as-is;
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* - on a retriable action advances st->attempt, computes st->delay_ms
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* (0 for RETRY_NOW; a jittered exponential backoff bounded by
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* cfg->max_retry_ms for RETRY_BACKOFF), reports the action in *action_out,
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* and returns true — UNLESS the retry budget (cfg->max_retries) is now
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* exhausted, in which case it returns false and, for a no-primary cause,
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* sets *rc = -E_XCE_NOT_READY (a transport-only cause keeps the last rc).
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*
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* It does NOT reset ctx state, drain wbuf, sleep, rotate, or invoke the rejoin
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* hook — those are the side-effecting wrapper's job (xcecli_retry_next) and
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* later tasks (3.2 state-reset/drain, 4.1 rejoin hook).
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*/
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bool xcecli_retry_decide(api_ctx_t* ac, int* rc, bool is_write,
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const xce_retry_config_t* cfg, xcecli_retry_t* st,
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xce_fo_action_t* action_out);
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/*
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* xcecli_retry_next(): the side-effecting wrapper the xcecli_* do/while loops
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* call. = xcecli_retry_decide() + (RETRY_BACKOFF: a real st->delay_ms sleep) +
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* (any retry: xce_failover_rotate(ac) + INFO log of the rotation target, 7.1) +
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* (budget exhaustion: WARN log of the attempt count, 7.2). Returns true → the
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* caller re-invokes its xce_* op; false → stop, *rc is final.
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*/
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bool xcecli_retry_next(api_ctx_t* ac, int* rc, bool is_write,
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xcecli_retry_t* st);
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/*
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* XCECLI_FAILOVER_CALL(ac, is_write, EXPR) — the shared XcecliRetryLoop wrapper
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* (task 5.1). Turns a one-shot reply-bearing xce_* call into a transparent
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* failover loop, holding the per-ctx lock (ac->failover.lock) for the FULL loop
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* duration so concurrent ops on a shared ctx are serialised (CI2): the
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* single-slot wbuf already implies one in-flight request per ctx; the lock makes
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* that explicit and covers the reconnect/rotate window.
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*
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* ac — api_ctx_t* (already NULL-checked by the caller's guard)
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* is_write — true for mutating ops (DUP-on-replay → success, 5.2), false reads
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* EXPR — the unchanged one-shot xce_* call, evaluated each iteration; its
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* rc is what the loop classifies and ultimately returns
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*
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* Evaluates to the final rc (>=0 success; -E_XCE_NOT_READY on no-primary budget
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* exhaustion; terminal errors surfaced as-is). Used as the RHS of `return`.
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*
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* Implemented as a GCC/clang statement-expression so it yields a value and keeps
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* each public xcecli_* signature/return convention intact (R1.3). The lock is
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* released on every exit path because the do/while always falls through to the
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* unlock before the result is produced.
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*/
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#define XCECLI_FAILOVER_CALL(ac, is_write, EXPR) \
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__extension__({ \
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api_ctx_t* _fo_ac = (ac); \
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xcecli_retry_t _fo_st = XCECLI_RETRY_INIT(_fo_ac); \
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int _fo_rc; \
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mylock_lock(&_fo_ac->failover.lock); \
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do { \
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_fo_rc = (EXPR); \
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} while ( \
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xcecli_retry_next(_fo_ac, &_fo_rc, (is_write), &_fo_st)); \
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mylock_unlock(&_fo_ac->failover.lock); \
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_fo_rc; \
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})
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/*
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* XCECLI_FAILOVER_CALL_COUNT(ac, EXPR) — sibling of XCECLI_FAILOVER_CALL for
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* xce_get-family calls (bug-1436).
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*
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* xce_get_with_condition (request.c) — and every xcecli_* wrapper built on it
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* (joblist, reslist, workerlist, resval, jobinfo) — returns a NON-NEGATIVE ROW
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* COUNT on success (`rc = getreply.nrows`), not a fixed 0/status code; a
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* negative return is the ONLY failure signal. XCECLI_FAILOVER_CALL assumes
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* every wrapped EXPR follows the "0 = success" status-code convention and
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* unconditionally feeds the raw return value through xce_failover_classify(),
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* which recognizes retriable/terminal outcomes by comparing MAGNITUDE against
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* fixed constants (E_XCE_* >= 10001, and POSIX errno values it deliberately
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* accepts in either sign — ECONNRESET=104, ETIMEDOUT=110, ECONNREFUSED=111,
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* client_failover.c fo_abs()). A joblist/reslist/workerlist/resval reply whose
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* row count happens to equal one of those constants (e.g. exactly 111 jobs ==
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* ECONNREFUSED) is silently misclassified as a transport failure on EVERY
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* call with that exact count — forcing a spurious xce_failover_rotate() to the
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* NEXT configured master even though the read fully succeeded. Since
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* get-class ops are primary-only, landing on a standby correctly (but
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* pointlessly) fails with E_XCE_STANDBY and rotates again; the cycle repeats
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* for every subsequent same-sized call in the same batch, burning the finite
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* max_retries budget (20) on self-inflicted churn until it coincides with a
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* genuine transient (e.g. a peer mid-restart after a just-completed election)
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* and exhausts the budget while rotating, surfacing a real
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* ECONNRESET/ECONNREFUSED to the caller — bug-1436 ("xce_joblist: Connection
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* reset by peer" immediately after a successful wait-primary; reproduced live
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* at exactly 111 tracked jobs, the first count in the /xce-test-ha soak's
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* arithmetic progression — 3 + 3*round — that lands on 111 == ECONNREFUSED).
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*
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* Fix: only enter the retry/classify loop when EXPR's raw result is NEGATIVE.
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* A non-negative result (0 or a genuine row count, of ANY magnitude) is
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* unconditionally success and returned as-is — it can never be misread as a
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* status code. A dead ctx (XCE_CTX_ERR) is still caught correctly: the per-op
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* XCE_CTX_RUN guard in xceapi.c makes EXPR itself return a negative -EINVAL in
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* that state, which enters the loop and is reclassified by
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* xcecli_retry_decide's dead-connection branch (checked before magnitude
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* classification, regardless of the stale *rc it was invoked with).
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*
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* is_write is hardcoded false: every xce_get-family op is a read.
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*/
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#define XCECLI_FAILOVER_CALL_COUNT(ac, EXPR) \
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__extension__({ \
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api_ctx_t* _fc_ac = (ac); \
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xcecli_retry_t _fc_st = XCECLI_RETRY_INIT(_fc_ac); \
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int _fc_rc; \
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mylock_lock(&_fc_ac->failover.lock); \
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do { \
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_fc_rc = (EXPR); \
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} while ((_fc_rc < 0) && \
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xcecli_retry_next(_fc_ac, &_fc_rc, /*is_write=*/false, \
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&_fc_st)); \
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mylock_unlock(&_fc_ac->failover.lock); \
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_fc_rc; \
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})
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/*
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* xcecli_ctx_recover (task 3.2) — repair the inner xce_ctx_t after a successful
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* reconnect so the next xce_* attempt can proceed. Socket-free (no I/O, no
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* sleep) so it is unit-testable; xcecli_retry_next invokes it after a successful
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* xce_failover_rotate(), before re-sending the interrupted op.
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*
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* CI2 (state reset): the transport-error path left ctx->state = XCE_CTX_ERR
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* (xcectx.c:174), which the per-op XCE_CTX_RUN guard rejects as -EINVAL
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* (xceapi.c) — the reported bug. recover restores XCE_CTX_RUN, but ONLY from
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* ERR: a DOWN/INIT ctx (deliberately stopped / not yet started) is left
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* as-is, and a RUN ctx is already fine.
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* CI1 (stale-reply drain): handle_disconnect may have injected a stale status
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* into the single-slot ctx->wbuf (xcectx.c:180). recover drains any pending
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* entry with a non-blocking cbuf_tryget so the next attempt's cbuf_get
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* cannot consume a prior-attempt reply. Reconnect closes the old fd first,
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* so the dead connection yields no further replies — this drain is enough.
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*
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* Returns 0 on success, -EINVAL on a NULL ac.
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*/
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int xcecli_ctx_recover(api_ctx_t* ac);
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/*
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* xcecli_ff_needs_reconnect (task 5.2) — PURE predicate for the fire-and-forget
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* best-effort reconnect decision. Fire-and-forget ops (notify_*, heartbeat, nop)
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* send a *_req only — there is NO reply to classify, so they must NOT go through
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* the full failover retry loop (no status classification, no no-primary backoff,
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* no retry budget; a heartbeat must never block on the backoff budget). Instead
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* the FF path makes AT MOST ONE best-effort transport reconnect when the
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* connection is KNOWN-DEAD, then does a single-shot send (which may be lost —
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* acceptable; redelivery is deferred to worker-rejoin-resync).
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*
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* The "known-dead" signal is ctx->state == XCE_CTX_ERR (set by the disconnect
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* path after a detected transport failure). Returns true ONLY for ERR so that a
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* deliberately-stopped (DOWN) or not-yet-started (INIT) ctx is never resurrected
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* by a fire-and-forget op. NULL-safe: returns false. Socket-free + side-effect
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* free so it is unit-testable.
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*/
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bool xcecli_ff_needs_reconnect(const api_ctx_t* ac);
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/*
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* XCECLI_FF_CALL(ac, EXPR) — the fire-and-forget best-effort wrapper (task 5.2).
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* Mirrors XCECLI_FAILOVER_CALL's per-ctx locking (CI2 — shared-ctx safety) but
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* is single-shot, NOT a retry loop: there is no reply to classify for an FF op,
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* so the full failover machinery (classification, no-primary backoff, retry
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* budget) is deliberately NOT used. Putting a heartbeat through the retry loop
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* would let it block on the no-primary backoff budget — explicitly forbidden.
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*
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* Behaviour, holding ac->failover.lock for the whole sequence:
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* 1. if the connection is KNOWN-DEAD (xcecli_ff_needs_reconnect), attempt ONE
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* best-effort reconnect: xce_failover_rotate(ac) + xcecli_ctx_recover(ac).
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* A failed reconnect is non-fatal — the send below is simply best-effort.
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* 2. evaluate EXPR exactly ONCE (the unchanged one-shot xce_* fire-and-forget
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* send) and yield its rc verbatim. A lost send rc is surfaced as-is, never
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* retried.
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*
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* ac — api_ctx_t* (already NULL-checked by the caller's guard)
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* EXPR — the unchanged one-shot xce_* *_req-only call
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*
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* Implemented as a GCC/clang statement-expression so it yields the send rc and
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* keeps each public xcecli_* signature/return convention intact (R1.3).
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*/
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#define XCECLI_FF_CALL(ac, EXPR) \
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__extension__({ \
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api_ctx_t* _ff_ac = (ac); \
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int _ff_rc; \
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mylock_lock(&_ff_ac->failover.lock); \
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if (xcecli_ff_needs_reconnect(_ff_ac)) { \
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(void)xce_failover_rotate(_ff_ac); \
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xcecli_ctx_recover(_ff_ac); \
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} \
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_ff_rc = (EXPR); \
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mylock_unlock(&_ff_ac->failover.lock); \
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_ff_rc; \
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})
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/*
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* xcecli_invoke_rejoin (task 4.1) — invoke the consumer rejoin hook once after a
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* successful reconnect/recovery and BEFORE the interrupted op resumes. Socket-
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* free (it only calls the stored callback), so it is unit-testable. The
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* xcecli_retry_next wrapper calls it AFTER xce_failover_rotate +
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* xcecli_ctx_recover and BEFORE re-sending the op.
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*
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* If no hook is registered (rejoin_cb == NULL, a pure client) it is a no-op and
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* returns 0 so the loop resumes directly. Otherwise it returns the callback's
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* rc: 0 to proceed, <0 to treat the rejoin as FAILED (the new primary rejected
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* the daemon's join) — the wrapper then does NOT resume but rotates/backs off on
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* the next iteration.
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*
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* Returns 0 on a successful (or absent) rejoin, the hook's <0 rc on a failed
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* rejoin, or -EINVAL on a NULL ac.
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*/
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int xcecli_invoke_rejoin(api_ctx_t* ac);
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#endif
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