Golang GCRequest.Span方法代碼示例

//.........這裏部分代碼省略.........
				resolveIntents, pushErr := ir.maybePushTransactions(ctxWithTimeout,
					item.intents, h, roachpb.PUSH_TOUCH, true /* skipInFlight */)

				// resolveIntents with poison=true because we're resolving
				// intents outside of the context of an EndTransaction.
				//
				// Naively, it doesn't seem like we need to poison the abort
				// cache since we're pushing with PUSH_TOUCH - meaning that
				// the primary way our Push leads to aborting intents is that
				// of the transaction having timed out (and thus presumably no
				// client being around any more, though at the time of writing
				// we don't guarantee that). But there's another path in which
				// the Push comes back successful, namely that of the
				// transaction already having been aborted by someone else, in
				// which case the client may still be running. Thus, we must
				// poison.
				if err := ir.resolveIntents(ctxWithTimeout, resolveIntents,
					true /* wait */, true /* poison */); err != nil {
					log.Warningf(context.TODO(), "%s: failed to resolve intents: %s", r, err)
					return
				}
				if pushErr != nil {
					log.Warningf(context.TODO(), "%s: failed to push during intent resolution: %s", r, pushErr)
					return
				}
			}); err != nil {
				log.Warningf(context.TODO(), "failed to resolve intents: %s", err)
				return
			}
		} else { // EndTransaction
			if err := stopper.RunLimitedAsyncTask(ir.sem, func() {
				ctxWithTimeout, cancel := context.WithTimeout(ctx, base.NetworkTimeout)
				defer cancel()

				// For EndTransaction, we know the transaction is finalized so
				// we can skip the push and go straight to the resolve.
				//
				// This mechanism assumes that when an EndTransaction fails,
				// the client makes no assumptions about the result. For
				// example, an attempt to explicitly rollback the transaction
				// may succeed (triggering this code path), but the result may
				// not make it back to the client.
				if err := ir.resolveIntents(ctxWithTimeout, item.intents,
					true /* wait */, false /* !poison */); err != nil {
					log.Warningf(context.TODO(), "%s: failed to resolve intents: %s", r, err)
					return
				}

				// We successfully resolved the intents, so we're able to GC from
				// the txn span directly.
				b := &client.Batch{}
				txn := item.intents[0].Txn
				txnKey := keys.TransactionKey(txn.Key, txn.ID)

				// This is pretty tricky. Transaction keys are range-local and
				// so they are encoded specially. The key range addressed by
				// (txnKey, txnKey.Next()) might be empty (since Next() does
				// not imply monotonicity on the address side). Instead, we
				// send this request to a range determined using the resolved
				// transaction anchor, i.e. if the txn is anchored on
				// /Local/RangeDescriptor/"a"/uuid, the key range below would
				// be ["a", "a\x00"). However, the first range is special again
				// because the above procedure results in KeyMin, but we need
				// at least KeyLocalMax.
				//
				// #7880 will address this by making GCRequest less special and
				// thus obviating the need to cook up an artificial range here.
				var gcArgs roachpb.GCRequest
				{
					key := keys.MustAddr(txn.Key)
					if localMax := keys.MustAddr(keys.LocalMax); key.Less(localMax) {
						key = localMax
					}
					endKey := key.Next()

					gcArgs.Span = roachpb.Span{
						Key:    key.AsRawKey(),
						EndKey: endKey.AsRawKey(),
					}
				}

				gcArgs.Keys = append(gcArgs.Keys, roachpb.GCRequest_GCKey{
					Key: txnKey,
				})
				b.AddRawRequest(&gcArgs)
				if err := ir.store.db.Run(b); err != nil {
					log.Warningf(
						context.TODO(),
						"could not GC completed transaction anchored at %s: %s",
						roachpb.Key(txn.Key), err,
					)
					return
				}
			}); err != nil {
				log.Warningf(context.TODO(), "failed to resolve intents: %s", err)
				return
			}
		}
	}
}