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core/bloombits: use single channel for shutdown (#20878) 

This replaces the two-stage shutdown scheme with the one we
use almost everywhere else: a single quit channel signalling
termination.

Co-authored-by: Felix Lange <fjl@twurst.com>
This commit is contained in:
ucwong 2020-07-29 19:49:12 +08:00 committed by GitHub
parent abf2d7d74f
commit 9e04c5ec83
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 24 additions and 35 deletions
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59
core/bloombits/matcher.go
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@ -155,7 +155,6 @@ func (m *Matcher) Start(ctx context.Context, begin, end uint64, results chan uin
session := &MatcherSession{
matcher: m,
quit: make(chan struct{}),
kill: make(chan struct{}),
ctx: ctx,
}
for _, scheduler := range m.schedulers {
@ -386,10 +385,8 @@ func (m *Matcher) distributor(dist chan *request, session *MatcherSession) {
requests = make(map[uint][]uint64) // Per-bit list of section requests, ordered by section number
unallocs = make(map[uint]struct{}) // Bits with pending requests but not allocated to any retriever
retrievers chan chan uint // Waiting retrievers (toggled to nil if unallocs is empty)
)
var (
allocs int // Number of active allocations to handle graceful shutdown requests
shutdown = session.quit // Shutdown request channel, will gracefully wait for pending requests
allocs int // Number of active allocations to handle graceful shutdown requests
shutdown = session.quit // Shutdown request channel, will gracefully wait for pending requests
)
// assign is a helper method fo try to assign a pending bit an actively
@ -409,15 +406,12 @@ func (m *Matcher) distributor(dist chan *request, session *MatcherSession) {
for {
select {
case <-shutdown:
// Graceful shutdown requested, wait until all pending requests are honoured
// Shutdown requested. No more retrievers can be allocated,
// but we still need to wait until all pending requests have returned.
shutdown = nil
if allocs == 0 {
return
}
shutdown = nil
case <-session.kill:
// Pending requests not honoured in time, hard terminate
return
case req := <-dist:
// New retrieval request arrived to be distributed to some fetcher process
@ -499,8 +493,9 @@ func (m *Matcher) distributor(dist chan *request, session *MatcherSession) {
assign(result.Bit)
}
}
// If we're in the process of shutting down, terminate
if allocs == 0 && shutdown == nil {
// End the session when all pending deliveries have arrived.
if shutdown == nil && allocs == 0 {
return
}
}
@ -514,7 +509,6 @@ type MatcherSession struct {
closer sync.Once // Sync object to ensure we only ever close once
quit chan struct{} // Quit channel to request pipeline termination
kill chan struct{} // Term channel to signal non-graceful forced shutdown
ctx context.Context // Context used by the light client to abort filtering
err atomic.Value // Global error to track retrieval failures deep in the chain
@ -529,7 +523,6 @@ func (s *MatcherSession) Close() {
s.closer.Do(func() {
// Signal termination and wait for all goroutines to tear down
close(s.quit)
time.AfterFunc(time.Second, func() { close(s.kill) })
s.pend.Wait()
})
}
@ -542,10 +535,10 @@ func (s *MatcherSession) Error() error {
return nil
}
// AllocateRetrieval assigns a bloom bit index to a client process that can either
// allocateRetrieval assigns a bloom bit index to a client process that can either
// immediately request and fetch the section contents assigned to this bit or wait
// a little while for more sections to be requested.
func (s *MatcherSession) AllocateRetrieval() (uint, bool) {
func (s *MatcherSession) allocateRetrieval() (uint, bool) {
fetcher := make(chan uint)
select {
@ -557,9 +550,9 @@ func (s *MatcherSession) AllocateRetrieval() (uint, bool) {
}
}
// PendingSections returns the number of pending section retrievals belonging to
// pendingSections returns the number of pending section retrievals belonging to
// the given bloom bit index.
func (s *MatcherSession) PendingSections(bit uint) int {
func (s *MatcherSession) pendingSections(bit uint) int {
fetcher := make(chan uint)
select {
@ -571,9 +564,9 @@ func (s *MatcherSession) PendingSections(bit uint) int {
}
}
// AllocateSections assigns all or part of an already allocated bit-task queue
// allocateSections assigns all or part of an already allocated bit-task queue
// to the requesting process.
func (s *MatcherSession) AllocateSections(bit uint, count int) []uint64 {
func (s *MatcherSession) allocateSections(bit uint, count int) []uint64 {
fetcher := make(chan *Retrieval)
select {
@ -589,14 +582,10 @@ func (s *MatcherSession) AllocateSections(bit uint, count int) []uint64 {
}
}
// DeliverSections delivers a batch of section bit-vectors for a specific bloom
// deliverSections delivers a batch of section bit-vectors for a specific bloom
// bit index to be injected into the processing pipeline.
func (s *MatcherSession) DeliverSections(bit uint, sections []uint64, bitsets [][]byte) {
select {
case <-s.kill:
return
case s.matcher.deliveries <- &Retrieval{Bit: bit, Sections: sections, Bitsets: bitsets}:
}
func (s *MatcherSession) deliverSections(bit uint, sections []uint64, bitsets [][]byte) {
s.matcher.deliveries <- &Retrieval{Bit: bit, Sections: sections, Bitsets: bitsets}
}
// Multiplex polls the matcher session for retrieval tasks and multiplexes it into
@ -608,17 +597,17 @@ func (s *MatcherSession) DeliverSections(bit uint, sections []uint64, bitsets []
func (s *MatcherSession) Multiplex(batch int, wait time.Duration, mux chan chan *Retrieval) {
for {
// Allocate a new bloom bit index to retrieve data for, stopping when done
bit, ok := s.AllocateRetrieval()
bit, ok := s.allocateRetrieval()
if !ok {
return
}
// Bit allocated, throttle a bit if we're below our batch limit
if s.PendingSections(bit) < batch {
if s.pendingSections(bit) < batch {
select {
case <-s.quit:
// Session terminating, we can't meaningfully service, abort
s.AllocateSections(bit, 0)
s.DeliverSections(bit, []uint64{}, [][]byte{})
s.allocateSections(bit, 0)
s.deliverSections(bit, []uint64{}, [][]byte{})
return
case <-time.After(wait):
@ -626,13 +615,13 @@ func (s *MatcherSession) Multiplex(batch int, wait time.Duration, mux chan chan
}
}
// Allocate as much as we can handle and request servicing
sections := s.AllocateSections(bit, batch)
sections := s.allocateSections(bit, batch)
request := make(chan *Retrieval)
select {
case <-s.quit:
// Session terminating, we can't meaningfully service, abort
s.DeliverSections(bit, sections, make([][]byte, len(sections)))
s.deliverSections(bit, sections, make([][]byte, len(sections)))
return
case mux <- request:
@ -644,7 +633,7 @@ func (s *MatcherSession) Multiplex(batch int, wait time.Duration, mux chan chan
s.err.Store(result.Error)
s.Close()
}
s.DeliverSections(result.Bit, result.Sections, result.Bitsets)
s.deliverSections(result.Bit, result.Sections, result.Bitsets)
}
}
}