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broken chkpt
This commit is contained in:
JackDoan
parent
e7f01390a3
commit
1719149594
16 changed files with 275 additions and 303 deletions
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@ -30,9 +30,9 @@ type SplitQueue struct {
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// chains and put them in the used ring.
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callEventFD eventfd.EventFD
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// usedChains is a chanel that receives [UsedElement]s for descriptor chains
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// UsedChains is a chanel that receives [UsedElement]s for descriptor chains
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// that were used by the device.
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usedChains chan UsedElement
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UsedChains chan UsedElement
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// moreFreeDescriptors is a channel that signals when any descriptors were
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// put back into the free chain of the descriptor table. This is used to
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@ -51,6 +51,7 @@ type SplitQueue struct {
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itemSize int
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epoll eventfd.Epoll
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more int
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}
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// NewSplitQueue allocates a new [SplitQueue] in memory. The given queue size
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@ -131,7 +132,7 @@ func NewSplitQueue(queueSize int) (_ *SplitQueue, err error) {
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}
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// Initialize channels.
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sq.usedChains = make(chan UsedElement, queueSize)
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sq.UsedChains = make(chan UsedElement, queueSize)
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sq.moreFreeDescriptors = make(chan struct{})
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sq.epoll, err = eventfd.NewEpoll()
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@ -190,20 +191,6 @@ func (sq *SplitQueue) CallEventFD() int {
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return sq.callEventFD.FD()
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}
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// UsedDescriptorChains returns the channel that receives [UsedElement]s for all
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// descriptor chains that were used by the device.
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//
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// Users of the [SplitQueue] should read from this channel, handle the used
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// descriptor chains and free them using [SplitQueue.FreeDescriptorChain] when
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// they're done with them. When this does not happen, the queue will run full
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// and any further calls to [SplitQueue.OfferDescriptorChain] will stall.
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//
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// When [SplitQueue.Close] is called, this channel will be closed as well.
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func (sq *SplitQueue) UsedDescriptorChains() chan UsedElement {
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sq.ensureInitialized()
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return sq.usedChains
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}
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// startConsumeUsedRing starts a goroutine that runs [consumeUsedRing].
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// A function is returned that can be used to gracefully cancel it. todo rename
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func (sq *SplitQueue) startConsumeUsedRing() func() error {
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@ -225,14 +212,49 @@ func (sq *SplitQueue) BlockAndGetHeads(ctx context.Context) ([]UsedElement, erro
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var n int
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var err error
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for ctx.Err() == nil {
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// Wait for a signal from the device.
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if n, err = sq.epoll.Block(); err != nil {
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return nil, fmt.Errorf("wait: %w", err)
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}
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if n > 0 {
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out := sq.usedRing.take()
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_ = sq.epoll.Clear() //???
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stillNeedToTake, out := sq.usedRing.take(-1)
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sq.more = stillNeedToTake
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if stillNeedToTake == 0 {
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_ = sq.epoll.Clear() //???
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}
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return out, nil
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}
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}
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return nil, ctx.Err()
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}
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func (sq *SplitQueue) BlockAndGetHeadsCapped(ctx context.Context, maxToTake int) ([]UsedElement, error) {
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var n int
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var err error
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for ctx.Err() == nil {
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//we have leftovers in the fridge
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if sq.more > 0 {
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stillNeedToTake, out := sq.usedRing.take(maxToTake)
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sq.more = stillNeedToTake
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if stillNeedToTake == 0 {
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_ = sq.epoll.Clear() //???
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}
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return out, nil
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}
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// Wait for a signal from the device.
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if n, err = sq.epoll.Block(); err != nil {
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return nil, fmt.Errorf("wait: %w", err)
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}
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if n > 0 {
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stillNeedToTake, out := sq.usedRing.take(maxToTake)
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sq.more = stillNeedToTake
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if stillNeedToTake == 0 {
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_ = sq.epoll.Clear() //???
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}
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return out, nil
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}
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}
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@ -240,12 +262,6 @@ func (sq *SplitQueue) BlockAndGetHeads(ctx context.Context) ([]UsedElement, erro
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return nil, ctx.Err()
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}
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// blockForMoreDescriptors blocks on a channel waiting for more descriptors to free up.
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// it is its own function so maybe it might show up in pprof
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func (sq *SplitQueue) blockForMoreDescriptors() {
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<-sq.moreFreeDescriptors
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}
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// OfferDescriptorChain offers a descriptor chain to the device which contains a
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// number of device-readable buffers (out buffers) and device-writable buffers
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// (in buffers).
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@ -271,63 +287,9 @@ func (sq *SplitQueue) blockForMoreDescriptors() {
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// used descriptor chains again using [SplitQueue.FreeDescriptorChain] when
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// they're done with them. When this does not happen, the queue will run full
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// and any further calls to [SplitQueue.OfferDescriptorChain] will stall.
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func (sq *SplitQueue) OfferDescriptorChain(outBuffers [][]byte, numInBuffers int, waitFree bool) (uint16, error) {
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func (sq *SplitQueue) OfferInDescriptorChains(numInBuffers int) (uint16, error) {
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sq.ensureInitialized()
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// TODO change this
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// Each descriptor can only hold a whole memory page, so split large out
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// buffers into multiple smaller ones.
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outBuffers = splitBuffers(outBuffers, sq.pageSize)
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// Synchronize the offering of descriptor chains. While the descriptor table
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// and available ring are synchronized on their own as well, this does not
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// protect us from interleaved calls which could cause reordering.
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// By locking here, we can ensure that all descriptor chains are made
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// available to the device in the same order as this method was called.
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sq.offerMutex.Lock()
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defer sq.offerMutex.Unlock()
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// Create a descriptor chain for the given buffers.
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var (
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head uint16
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err error
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)
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for {
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head, err = sq.descriptorTable.createDescriptorChain(outBuffers, numInBuffers)
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if err == nil {
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break
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}
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// I don't wanna use errors.Is, it's slow
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//goland:noinspection GoDirectComparisonOfErrors
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if err == ErrNotEnoughFreeDescriptors {
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if waitFree {
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// Wait for more free descriptors to be put back into the queue.
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// If the number of free descriptors is still not sufficient, we'll
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// land here again.
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sq.blockForMoreDescriptors()
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continue
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} else {
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return 0, err
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}
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}
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return 0, fmt.Errorf("create descriptor chain: %w", err)
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}
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// Make the descriptor chain available to the device.
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sq.availableRing.offer([]uint16{head})
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// Notify the device to make it process the updated available ring.
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if err := sq.kickEventFD.Kick(); err != nil {
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return head, fmt.Errorf("notify device: %w", err)
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}
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return head, nil
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}
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func (sq *SplitQueue) OfferInDescriptorChains(numInBuffers int, waitFree bool) (uint16, error) {
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sq.ensureInitialized()
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// Synchronize the offering of descriptor chains. While the descriptor table
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// and available ring are synchronized on their own as well, this does not
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// protect us from interleaved calls which could cause reordering.
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@ -350,21 +312,14 @@ func (sq *SplitQueue) OfferInDescriptorChains(numInBuffers int, waitFree bool) (
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// I don't wanna use errors.Is, it's slow
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//goland:noinspection GoDirectComparisonOfErrors
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if err == ErrNotEnoughFreeDescriptors {
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if waitFree {
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// Wait for more free descriptors to be put back into the queue.
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// If the number of free descriptors is still not sufficient, we'll
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// land here again.
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sq.blockForMoreDescriptors()
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continue
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} else {
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return 0, err
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}
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return 0, err
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} else {
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return 0, fmt.Errorf("create descriptor chain: %w", err)
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}
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return 0, fmt.Errorf("create descriptor chain: %w", err)
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}
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// Make the descriptor chain available to the device.
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sq.availableRing.offer([]uint16{head})
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sq.availableRing.offerSingle(head)
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// Notify the device to make it process the updated available ring.
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if err := sq.kickEventFD.Kick(); err != nil {
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@ -374,7 +329,7 @@ func (sq *SplitQueue) OfferInDescriptorChains(numInBuffers int, waitFree bool) (
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return head, nil
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}
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func (sq *SplitQueue) OfferOutDescriptorChains(prepend []byte, outBuffers [][]byte, waitFree bool) ([]uint16, error) {
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func (sq *SplitQueue) OfferOutDescriptorChains(prepend []byte, outBuffers [][]byte) ([]uint16, error) {
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sq.ensureInitialized()
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// TODO change this
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@ -408,15 +363,11 @@ func (sq *SplitQueue) OfferOutDescriptorChains(prepend []byte, outBuffers [][]by
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// I don't wanna use errors.Is, it's slow
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//goland:noinspection GoDirectComparisonOfErrors
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if err == ErrNotEnoughFreeDescriptors {
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if waitFree {
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// Wait for more free descriptors to be put back into the queue.
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// If the number of free descriptors is still not sufficient, we'll
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// land here again.
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sq.blockForMoreDescriptors()
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continue
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} else {
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return nil, err
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}
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// Wait for more free descriptors to be put back into the queue.
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// If the number of free descriptors is still not sufficient, we'll
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// land here again.
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<-sq.moreFreeDescriptors
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continue
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}
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return nil, fmt.Errorf("create descriptor chain: %w", err)
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}
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@ -473,7 +424,7 @@ func (sq *SplitQueue) FreeDescriptorChain(head uint16) error {
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// There is more free room in the descriptor table now.
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// This is a fire-and-forget signal, so do not block when nobody listens.
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select {
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select { //todo eliminate
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case sq.moreFreeDescriptors <- struct{}{}:
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default:
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}
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@ -481,7 +432,7 @@ func (sq *SplitQueue) FreeDescriptorChain(head uint16) error {
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return nil
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}
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func (sq *SplitQueue) FreeAndOfferDescriptorChains(head uint16) error {
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func (sq *SplitQueue) RecycleDescriptorChains(chains []UsedElement) error {
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sq.ensureInitialized()
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//todo I don't think we need this here?
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@ -500,7 +451,7 @@ func (sq *SplitQueue) FreeAndOfferDescriptorChains(head uint16) error {
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//}
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// Make the descriptor chain available to the device.
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sq.availableRing.offer([]uint16{head})
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sq.availableRing.offerElements(chains)
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// Notify the device to make it process the updated available ring.
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if err := sq.kickEventFD.Kick(); err != nil {
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@ -524,7 +475,7 @@ func (sq *SplitQueue) Close() error {
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// The stop function blocked until the goroutine ended, so the channel
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// can now safely be closed.
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close(sq.usedChains)
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close(sq.UsedChains)
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// Make sure that this code block is executed only once.
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sq.stop = nil
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