ResourceOwner Overview

ResourceOwner 用于“统一管理非内存资源生命周期”的机制，确保资源在事务/执行结束或异常时被正确释放（手动实现 RAII ）。

• 资源分散在各模块（buffer / lock / snapshot / file …）
• 执行中可能随时中断
• 需要统一兜底释放

核心设计

树结构（作用域）

TopTransaction
  ├── SubTransaction
  └── Portal

分阶段释放(保证资源依赖顺序正确)

BEFORE LOCKS → LOCKS → AFTER LOCKS

核心结构

/*
 * ResourceOwner objects look like this
 */
typedef struct ResourceOwnerData
{
    ResourceOwner parent;       /* NULL if no parent (toplevel owner) */
    ResourceOwner firstchild;   /* head of linked list of children */
    ResourceOwner nextchild;    /* next child of same parent */
    const char *name;           /* name (just for debugging) */

    /* We have built-in support for remembering: */
    ResourceArray bufferarr;    /* owned buffers */
    ResourceArray bufferioarr;  /* in-progress buffer IO */
    ResourceArray catrefarr;    /* catcache references */
    ResourceArray catlistrefarr;    /* catcache-list pins */
    ResourceArray relrefarr;    /* relcache references */
    ResourceArray planrefarr;   /* plancache references */
    ResourceArray tupdescarr;   /* tupdesc references */
    ResourceArray snapshotarr;  /* snapshot references */
    ResourceArray filearr;      /* open temporary files */
    ResourceArray dsmarr;       /* dynamic shmem segments */
    ResourceArray jitarr;       /* JIT contexts */
    ResourceArray cryptohasharr;    /* cryptohash contexts */
    ResourceArray hmacarr;      /* HMAC contexts */

    /* We can remember up to MAX_RESOWNER_LOCKS references to local locks. */
    int         nlocks;         /* number of owned locks */
    LOCALLOCK  *locks[MAX_RESOWNER_LOCKS];  /* list of owned locks */
}           ResourceOwnerData;

核心接口

ResourceOwnerCreate
ResourceOwnerRelease
ResourceOwnerDelete
ResourceOwnerRemember_____
ResourceOwnerForget_____

BEGIN;

INSERT INTO t VALUES (0);

SAVEPOINT sp1;
INSERT INTO t VALUES (1);
ROLLBACK TO sp1;


SAVEPOINT sp2;
INSERT INTO t VALUES (2);
COMMIT;