Files
mesh-controller/cmd/mesh-controller/composer.go
T
jschoubben 8114cee2af
mesh/delivery closed: a newer head of the same pull request
mesh/check pass 8114cee2af47 on 0fff3efd4e0b | unit 959 run, 172 kept, 2 skipped | integration 1615 run, 236 kept, 7 skipped | over bound: integration…
Give each caller of a pass its own nodes' errors and write the grants whenever asked; a wake during a take-in makes it look once more (issue 1945)
2026-10-25 12:44:28 +01:00

106 lines
3.1 KiB
Go

package main
import (
"context"
"errors"
"sort"
"sync"
)
// **One composer, one pass at a time, each node once per pass** (issue 1945). A done key's take-in registers its module
// and asks the composer for its nodes; the composer gathers every node asked for while a pass runs and composes them in
// the next pass, in one composition of each node, then writes the grants once. Before, each take-in of a burst composed
// every node of its module itself, at once: they collided on the compositions' revisions ("wrong last sequence … key
// revision mismatch"), retried every 30 s, and the take-in that mattered waited behind them (2026-10-25 at 11:18 and
// 12:32). A caller waits for the pass that began after it asked, and hears that pass's error.
type composer struct {
composeNodes func(ctx context.Context, nodes []string) map[string]error
writeGrants func(ctx context.Context) error
mu sync.Mutex
pending map[string]bool
grants bool
waiters []waiter
wake chan struct{}
}
// waiter is a caller waiting for its pass: the nodes it asked for, whether it asked for the grants, and where its answer
// goes.
type waiter struct {
nodes []string
grants bool
done chan error
}
func newComposer(compose func(context.Context, []string) map[string]error, grants func(context.Context) error) *composer {
return &composer{composeNodes: compose, writeGrants: grants, pending: map[string]bool{}, wake: make(chan struct{}, 1)}
}
// compose asks for the nodes to be composed, and the grants written after when grants is true, and waits for the pass
// that does it, with the errors of its own nodes alone.
func (c *composer) compose(ctx context.Context, nodes []string, grants bool) error {
done := make(chan error, 1)
c.mu.Lock()
for _, n := range nodes {
c.pending[n] = true
}
c.grants = c.grants || grants
c.waiters = append(c.waiters, waiter{nodes: nodes, grants: grants, done: done})
c.mu.Unlock()
select {
case c.wake <- struct{}{}:
default:
}
select {
case err := <-done:
return err
case <-ctx.Done():
return ctx.Err()
}
}
// run makes the passes until ctx ends: each takes everything asked for since the last began.
func (c *composer) run(ctx context.Context) {
for {
select {
case <-ctx.Done():
return
case <-c.wake:
}
c.mu.Lock()
nodes := make([]string, 0, len(c.pending))
for n := range c.pending {
nodes = append(nodes, n)
}
grants, waiters := c.grants, c.waiters
c.pending, c.grants, c.waiters = map[string]bool{}, false, nil
c.mu.Unlock()
if len(waiters) == 0 {
continue
}
sort.Strings(nodes)
var failed map[string]error
if len(nodes) > 0 {
failed = c.composeNodes(ctx, nodes)
}
// The grants whenever a caller asked for them, whatever a node's composition said: a node that failed fails its
// own callers alone (issue 1945).
var grantsErr error
if grants {
grantsErr = c.writeGrants(ctx)
}
for _, w := range waiters {
var errs []error
for _, n := range w.nodes {
if err := failed[n]; err != nil {
errs = append(errs, err)
}
}
if w.grants && grantsErr != nil {
errs = append(errs, grantsErr)
}
w.done <- errors.Join(errs...)
}
}
}