110 lines
3.4 KiB
Go
110 lines
3.4 KiB
Go
// Copyright 2022 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package tracers
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import (
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"fmt"
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"sync"
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)
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// stateTracker is an auxiliary tool used to cache the release functions of all
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// used trace states, and to determine whether the creation of trace state needs
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// to be paused in case there are too many states waiting for tracing.
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type stateTracker struct {
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limit int // Maximum number of states allowed waiting for tracing
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oldest uint64 // The number of the oldest state which is still using for trace
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used []bool // List of flags indicating whether the trace state has been used up
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releases []StateReleaseFunc // List of trace state release functions waiting to be called
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cond *sync.Cond
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lock *sync.RWMutex
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}
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// newStateTracker initializes the tracker with provided state limits and
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// the number of the first state that will be used.
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func newStateTracker(limit int, oldest uint64) *stateTracker {
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lock := new(sync.RWMutex)
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return &stateTracker{
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limit: limit,
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oldest: oldest,
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used: make([]bool, limit),
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cond: sync.NewCond(lock),
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lock: lock,
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}
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}
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// releaseState marks the state specified by the number as released and caches
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// the corresponding release functions internally.
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func (t *stateTracker) releaseState(number uint64, release StateReleaseFunc) {
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t.lock.Lock()
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defer t.lock.Unlock()
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// Set the state as used, the corresponding flag is indexed by
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// the distance between the specified state and the oldest state
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// which is still using for trace.
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t.used[int(number-t.oldest)] = true
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// If the oldest state is used up, update the oldest marker by moving
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// it to the next state which is not used up.
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if number == t.oldest {
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var count int
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for _, used := range t.used {
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if !used {
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break
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}
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count += 1
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}
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t.oldest += uint64(count)
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copy(t.used, t.used[count:])
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// Clean up the array tail since they are useless now.
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for i := t.limit - count; i < t.limit; i++ {
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t.used[i] = false
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}
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// Fire the signal to all waiters that oldest marker is updated.
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t.cond.Broadcast()
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}
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t.releases = append(t.releases, release)
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}
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// callReleases invokes all cached release functions.
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func (t *stateTracker) callReleases() {
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t.lock.Lock()
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defer t.lock.Unlock()
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for _, release := range t.releases {
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release()
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}
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t.releases = t.releases[:0]
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}
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// wait blocks until the accumulated trace states are less than the limit.
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func (t *stateTracker) wait(number uint64) error {
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t.lock.Lock()
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defer t.lock.Unlock()
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for {
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if number < t.oldest {
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return fmt.Errorf("invalid state number %d head %d", number, t.oldest)
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}
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if number < t.oldest+uint64(t.limit) {
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// number is now within limit, wait over
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return nil
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}
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t.cond.Wait()
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}
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}
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