From 491ed0f085c0ac7862a4442ad303a8648e0ee582 Mon Sep 17 00:00:00 2001 From: Nathan VanBenschoten Date: Tue, 2 Aug 2022 23:37:19 -0400 Subject: [PATCH] gossip: provide online method to clear leaked gossip infos Fixes #85013. Needed for cockroachlabs/support#1709. This commit introduces a new `crdb_internal.unsafe_clear_gossip_info` builtin function which allows admin users to manually clear info objects from the cluster's gossip network. The function does so by re-gossiping an identical value for the specified key but with a TTL that is long enough to reasonably ensure full propagation to all nodes in the cluster but short enough to expire quickly once propagated. The function is best-effort. It is possible for the info object with the low TTL to fail to reach full propagation before reaching its TTL. For instance, this is possible during a transient network partition. The effect of this is that the existing gossip info object with a higher (or no) TTL would remain in the gossip network on some nodes and may eventually propagate back out to other nodes once the partition heals. Release note: None --- docs/generated/sql/functions.md | 2 + pkg/gossip/gossip.go | 37 +++++++++++++++++++ pkg/gossip/gossip_test.go | 20 ++++++++++ pkg/sql/BUILD.bazel | 1 + pkg/sql/conn_executor.go | 1 + pkg/sql/gossip.go | 25 +++++++++++++ .../testdata/logic_test/crdb_internal | 6 +++ pkg/sql/planner.go | 1 + pkg/sql/sem/builtins/builtins.go | 21 +++++++++++ pkg/sql/sem/tree/eval.go | 11 ++++++ 10 files changed, 125 insertions(+) create mode 100644 pkg/sql/gossip.go diff --git a/docs/generated/sql/functions.md b/docs/generated/sql/functions.md index 90d467b5f221..55a1b49cc9eb 100644 --- a/docs/generated/sql/functions.md +++ b/docs/generated/sql/functions.md @@ -2904,6 +2904,8 @@ table. Returns an error if validation fails.

crdb_internal.trace_id() → int

Returns the current trace ID or an error if no trace is open.

 +crdb_internal.unsafe_clear_gossip_info(key: string) → bool

This function is used only by CockroachDB’s developers for testing purposes.

+ current_database() → string

Returns the current database.

 current_schema() → string

Returns the current schema.

diff --git a/pkg/gossip/gossip.go b/pkg/gossip/gossip.go index 41d2f6b8d296..d3c5dcb3ca49 100644 --- a/pkg/gossip/gossip.go +++ b/pkg/gossip/gossip.go @@ -1068,6 +1068,43 @@ func (g *Gossip) GetInfoProto(key string, msg protoutil.Message) error { return protoutil.Unmarshal(bytes, msg) } +// TryClearInfo attempts to clear an info object from the cluster's gossip +// network. It does so by retrieving the object with the corresponding key. If +// one does not exist, there's nothing to do and the method returns false. +// Otherwise, the method re-gossips the same key-value pair with a TTL that is +// long enough to reasonably ensure full propagation to all nodes in the cluster +// but short enough to expire quickly once propagated. +// +// The method is best-effort. It is possible for the info object with the low +// TTL to fail to reach full propagation before reaching its TTL. For instance, +// this is possible during a transient network partition. The effect of this is +// that the existing gossip info object with a higher (or no) TTL would remain +// in the gossip network on some nodes and may eventually propagate back out to +// other nodes once the partition heals. +func (g *Gossip) TryClearInfo(key string) (bool, error) { + // Long enough to propagate to all nodes, short enough to expire quickly. + const ttl = 1 * time.Minute + return g.tryClearInfoWithTTL(key, ttl) +} + +func (g *Gossip) tryClearInfoWithTTL(key string, ttl time.Duration) (bool, error) { + val, err := g.GetInfo(key) + if err != nil { + if errors.HasType(err, KeyNotPresentError{}) { + // Info object not known on this node. We can't force a deletion + // preemptively, e.g. with a poison entry, because we do not have a valid + // value object to populate and consumers may make assumptions about the + // format of the value. + return false, nil + } + return false, err + } + if err := g.AddInfo(key, val, ttl); err != nil { + return false, err + } + return true, nil +} + // InfoOriginatedHere returns true iff the latest info for the provided key // originated on this node. This is useful for ensuring that the system config // is regossiped as soon as possible when its lease changes hands. diff --git a/pkg/gossip/gossip_test.go b/pkg/gossip/gossip_test.go index 8929a02ac27d..64532c3ea426 100644 --- a/pkg/gossip/gossip_test.go +++ b/pkg/gossip/gossip_test.go @@ -859,6 +859,26 @@ func TestGossipPropagation(t *testing.T) { } return nil }) + + mustClear := func(g *Gossip, key string) { + if _, err := g.tryClearInfoWithTTL(key, 3*time.Second); err != nil { + t.Fatal(err) + } + } + + // Clear both entries. Verify that both are removed from the gossip network. + mustClear(local, "local") + mustClear(remote, "remote") + testutils.SucceedsSoon(t, func() error { + for gName, g := range map[string]*Gossip{"local": local, "remote": remote} { + for _, key := range []string{"local", "remote"} { + if getInfo(g, key) != nil { + return fmt.Errorf("%s info %q not cleared", gName, key) + } + } + } + return nil + }) } // Test whether propagation of an info that was generated by a prior diff --git a/pkg/sql/BUILD.bazel b/pkg/sql/BUILD.bazel index 9c9653f959ce..1a8085608605 100644 --- a/pkg/sql/BUILD.bazel +++ b/pkg/sql/BUILD.bazel @@ -103,6 +103,7 @@ go_library( "explain_vec.go", "export.go", "filter.go", + "gossip.go", "grant_revoke.go", "grant_role.go", "group.go", diff --git a/pkg/sql/conn_executor.go b/pkg/sql/conn_executor.go index c108cb1e57db..444dfefa07fe 100644 --- a/pkg/sql/conn_executor.go +++ b/pkg/sql/conn_executor.go @@ -2455,6 +2455,7 @@ func (ex *connExecutor) initEvalCtx(ctx context.Context, evalCtx *extendedEvalCo Tenant: p, Regions: p, JoinTokenCreator: p, + Gossip: p, PreparedStatementState: &ex.extraTxnState.prepStmtsNamespace, SessionDataStack: ex.sessionDataStack, ReCache: ex.server.reCache, diff --git a/pkg/sql/gossip.go b/pkg/sql/gossip.go new file mode 100644 index 000000000000..c4a16243678c --- /dev/null +++ b/pkg/sql/gossip.go @@ -0,0 +1,25 @@ +// Copyright 2022 The Cockroach Authors. +// +// Use of this software is governed by the Business Source License +// included in the file licenses/BSL.txt. +// +// As of the Change Date specified in that file, in accordance with +// the Business Source License, use of this software will be governed +// by the Apache License, Version 2.0, included in the file +// licenses/APL.txt. + +package sql + +import "context" + +// TryClearGossipInfo implements the tree.GossipOperator interface. +func (p *planner) TryClearGossipInfo(ctx context.Context, key string) (bool, error) { + g, err := p.ExecCfg().Gossip.OptionalErr(0 /* issue */) + if err != nil { + return false, err + } + if err := p.RequireAdminRole(ctx, "try clear gossip info"); err != nil { + return false, err + } + return g.TryClearInfo(key) +} diff --git a/pkg/sql/logictest/testdata/logic_test/crdb_internal b/pkg/sql/logictest/testdata/logic_test/crdb_internal index 554f1ad8addb..494dea7d337e 100644 --- a/pkg/sql/logictest/testdata/logic_test/crdb_internal +++ b/pkg/sql/logictest/testdata/logic_test/crdb_internal @@ -928,3 +928,9 @@ statement ok CREATE TABLE t69684(a NAME); INSERT INTO t69684 VALUES ('foo'); SELECT * FROM t69684 WHERE crdb_internal.increment_feature_counter(a) + +# Exercise unsafe gossip builtin functions. +query B +SELECT crdb_internal.unsafe_clear_gossip_info('unknown key') +---- +false diff --git a/pkg/sql/planner.go b/pkg/sql/planner.go index 57c5767b9354..0b6423096e46 100644 --- a/pkg/sql/planner.go +++ b/pkg/sql/planner.go @@ -398,6 +398,7 @@ func newInternalPlanner( p.extendedEvalCtx.Tenant = p p.extendedEvalCtx.Regions = p p.extendedEvalCtx.JoinTokenCreator = p + p.extendedEvalCtx.Gossip = p p.extendedEvalCtx.ClusterID = execCfg.ClusterID() p.extendedEvalCtx.ClusterName = execCfg.RPCContext.ClusterName() p.extendedEvalCtx.NodeID = execCfg.NodeID diff --git a/pkg/sql/sem/builtins/builtins.go b/pkg/sql/sem/builtins/builtins.go index e7028e6bb239..41cef8f0547b 100644 --- a/pkg/sql/sem/builtins/builtins.go +++ b/pkg/sql/sem/builtins/builtins.go @@ -4667,6 +4667,27 @@ value if you rely on the HLC for accuracy.`, }, ), + "crdb_internal.unsafe_clear_gossip_info": makeBuiltin( + tree.FunctionProperties{Category: categorySystemInfo}, + tree.Overload{ + Types: tree.ArgTypes{{"key", types.String}}, + ReturnType: tree.FixedReturnType(types.Bool), + Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) { + key, ok := tree.AsDString(args[0]) + if !ok { + return nil, errors.Newf("expected string value, got %T", args[0]) + } + ok, err := ctx.Gossip.TryClearGossipInfo(ctx.Context, string(key)) + if err != nil { + return nil, err + } + return tree.MakeDBool(tree.DBool(ok)), nil + }, + Info: "This function is used only by CockroachDB's developers for testing purposes.", + Volatility: tree.VolatilityVolatile, + }, + ), + "crdb_internal.encode_key": makeBuiltin( tree.FunctionProperties{Category: categorySystemInfo}, tree.Overload{ diff --git a/pkg/sql/sem/tree/eval.go b/pkg/sql/sem/tree/eval.go index 59b370aa43cc..240144adee38 100644 --- a/pkg/sql/sem/tree/eval.go +++ b/pkg/sql/sem/tree/eval.go @@ -3431,6 +3431,15 @@ type JoinTokenCreator interface { CreateJoinToken(ctx context.Context) (string, error) } +// GossipOperator is capable of manipulating the cluster's gossip network. The +// methods will return errors when run by any tenant other than the system +// tenant. +type GossipOperator interface { + // TryClearGossipInfo attempts to clear an info object from the cluster's + // gossip network. + TryClearGossipInfo(ctx context.Context, key string) (bool, error) +} + // EvalContextTestingKnobs contains test knobs. type EvalContextTestingKnobs struct { // AssertFuncExprReturnTypes indicates whether FuncExpr evaluations @@ -3582,6 +3591,8 @@ type EvalContext struct { JoinTokenCreator JoinTokenCreator + Gossip GossipOperator + PreparedStatementState PreparedStatementState // The transaction in which the statement is executing.