forked from wrenn/wrenn
pptx704
962860ba74
envd crashes with "fatal error: bad summary data" after Firecracker snapshot/restore because the page allocator radix tree is inconsistent when vCPUs are frozen mid-allocation. The port scanner goroutine allocates heavily every second, making it the primary trigger. Add POST /snapshot/prepare to envd — the host agent calls it before vm.Pause to quiesce continuous goroutines and force GC. On restore, PostInit restarts the port subsystem via the existing /init endpoint. - New PortSubsystem abstraction with Start/Stop/Restart lifecycle - Context-based goroutine cancellation (replaces irreversible channel close) - Context-aware Signal to prevent scanner/forwarder deadlock - Fix forwarder goroutine leak (was spinning forever on closed channel) - Kill socat children on stop to prevent orphans across snapshots - Fix double cmd.Wait panic (exec.Command instead of CommandContext)
107 lines
2.5 KiB
Go
107 lines
2.5 KiB
Go
// SPDX-License-Identifier: Apache-2.0
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// Modifications by M/S Omukk
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package port
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import (
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"context"
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"runtime"
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"runtime/debug"
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"sync"
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"time"
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"github.com/rs/zerolog"
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"git.omukk.dev/wrenn/sandbox/envd/internal/services/cgroups"
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)
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// PortSubsystem owns the port scanner and forwarder lifecycle.
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// It supports stop/restart across Firecracker snapshot/restore cycles.
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type PortSubsystem struct {
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logger *zerolog.Logger
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cgroupManager cgroups.Manager
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period time.Duration
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mu sync.Mutex
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cancel context.CancelFunc
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wg *sync.WaitGroup // per-cycle WaitGroup; nil when not running
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running bool
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}
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// NewPortSubsystem creates a new PortSubsystem. Call Start() to begin scanning.
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func NewPortSubsystem(logger *zerolog.Logger, cgroupManager cgroups.Manager, period time.Duration) *PortSubsystem {
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return &PortSubsystem{
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logger: logger,
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cgroupManager: cgroupManager,
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period: period,
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}
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}
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// Start creates a fresh scanner and forwarder, launching their goroutines.
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// Safe to call multiple times; does nothing if already running.
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func (p *PortSubsystem) Start(parentCtx context.Context) {
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p.mu.Lock()
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defer p.mu.Unlock()
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if p.running {
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return
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}
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ctx, cancel := context.WithCancel(parentCtx)
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p.cancel = cancel
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p.running = true
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// Allocate a fresh WaitGroup for this lifecycle so a concurrent Stop
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// on the previous cycle's WaitGroup cannot interfere.
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wg := &sync.WaitGroup{}
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p.wg = wg
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scanner := NewScanner(p.period)
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forwarder := NewForwarder(p.logger, scanner, p.cgroupManager)
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wg.Add(2)
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go func() {
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defer wg.Done()
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forwarder.StartForwarding(ctx)
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}()
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go func() {
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defer wg.Done()
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scanner.ScanAndBroadcast(ctx)
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}()
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}
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// Stop quiesces the scanner and forwarder goroutines and forces a GC cycle
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// to put the Go runtime's page allocator in a consistent state before snapshot.
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// Blocks until both goroutines have exited. Safe to call if already stopped.
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func (p *PortSubsystem) Stop() {
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p.mu.Lock()
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if !p.running {
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p.mu.Unlock()
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return
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}
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cancelFn := p.cancel
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wg := p.wg
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p.cancel = nil
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p.wg = nil
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p.running = false
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p.mu.Unlock()
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cancelFn()
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wg.Wait()
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// Force two GC cycles to ensure all spans are swept and the page
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// allocator summary tree is fully consistent before the VM is frozen.
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runtime.GC()
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runtime.GC()
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debug.FreeOSMemory()
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}
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// Restart stops the subsystem (if running) and starts it again with a fresh
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// scanner and forwarder. Used after snapshot restore via PostInit.
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func (p *PortSubsystem) Restart(parentCtx context.Context) {
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p.Stop()
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p.Start(parentCtx)
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}
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