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|
package cache
import (
"context"
"errors"
"io"
"os"
"path/filepath"
"sync"
"github.com/grpc-ecosystem/go-grpc-middleware/logging/logrus/ctxlogrus"
"github.com/prometheus/client_golang/prometheus"
"gitlab.com/gitlab-org/gitaly/v14/internal/dontpanic"
"gitlab.com/gitlab-org/gitaly/v14/internal/gitaly/config"
"gitlab.com/gitlab-org/gitaly/v14/internal/gitaly/storage"
"gitlab.com/gitlab-org/gitaly/v14/internal/safe"
"gitlab.com/gitlab-org/gitaly/v14/proto/go/gitalypb"
"google.golang.org/protobuf/proto"
)
// maps a cache path to the number of active writers
type activeFiles struct {
*sync.Mutex
m map[string]int
}
// trackFile returns a function that indicates if the current
// writing of a file is the last known one, which
// would indicate the current write is the "winner".
func (af activeFiles) trackFile(path string) func() bool {
af.Lock()
defer af.Unlock()
af.m[path]++
return func() bool {
af.Lock()
defer af.Unlock()
af.m[path]--
winner := af.m[path] == 0
if winner {
delete(af.m, path) // reclaim memory
}
return winner
}
}
type cacheConfig struct {
disableMoveAndClear bool // only used to disable move and clear in tests
disableWalker bool // only used to disable object walker in tests
}
// Option is an option for the cache.
type Option func(*cacheConfig)
// withDisabledMoveAndClear disables the initial move and cleanup of preexisting cache directories.
// This option is only for test purposes.
func withDisabledMoveAndClear() Option {
return func(cfg *cacheConfig) {
cfg.disableMoveAndClear = true
}
}
// withDisabledWalker disables the cache walker which cleans up the cache asynchronously. This
// option is only for test purposes.
func withDisabledWalker() Option {
return func(cfg *cacheConfig) {
cfg.disableWalker = true
}
}
// DiskCache stores and retrieves byte streams for repository related RPCs
type DiskCache struct {
locator storage.Locator
storages []config.Storage
keyer leaseKeyer
af activeFiles
cacheConfig cacheConfig
walkersDone chan struct{}
walkerLoops []*dontpanic.Forever
requestTotals prometheus.Counter
missTotals prometheus.Counter
bytesStoredtotals prometheus.Counter
bytesFetchedtotals prometheus.Counter
bytesLoserTotals prometheus.Counter
errTotal *prometheus.CounterVec
walkerCheckTotal prometheus.Counter
walkerRemovalTotal prometheus.Counter
walkerErrorTotal prometheus.Counter
walkerEmptyDirTotal prometheus.Counter
walkerEmptyDirRemovalTotal prometheus.Counter
}
// New will create a new DiskCache with the given Keyer.
func New(cfg config.Cfg, locator storage.Locator, opts ...Option) *DiskCache {
var cacheConfig cacheConfig
for _, opt := range opts {
opt(&cacheConfig)
}
cache := &DiskCache{
locator: locator,
storages: cfg.Storages,
af: activeFiles{
Mutex: &sync.Mutex{},
m: map[string]int{},
},
cacheConfig: cacheConfig,
walkersDone: make(chan struct{}),
requestTotals: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_requests_total",
Help: "Total number of disk cache requests",
},
),
missTotals: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_miss_total",
Help: "Total number of disk cache misses",
},
),
bytesStoredtotals: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_bytes_stored_total",
Help: "Total number of disk cache bytes stored",
},
),
bytesFetchedtotals: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_bytes_fetched_total",
Help: "Total number of disk cache bytes fetched",
},
),
bytesLoserTotals: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_bytes_loser_total",
Help: "Total number of disk cache bytes from losing writes",
},
),
errTotal: prometheus.NewCounterVec(
prometheus.CounterOpts{
Name: "gitaly_diskcache_errors_total",
Help: "Total number of errors encountered by disk cache",
},
[]string{"error"},
),
walkerCheckTotal: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_walker_check_total",
Help: "Total number of events during diskcache filesystem walks",
},
),
walkerRemovalTotal: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_walker_removal_total",
Help: "Total number of events during diskcache filesystem walks",
},
),
walkerErrorTotal: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_walker_error_total",
Help: "Total number of errors during diskcache filesystem walks",
},
),
walkerEmptyDirTotal: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_walker_empty_dir_total",
Help: "Total number of empty directories encountered",
},
),
walkerEmptyDirRemovalTotal: prometheus.NewCounter(
prometheus.CounterOpts{
Name: "gitaly_diskcache_walker_empty_dir_removal_total",
Help: "Total number of empty directories removed",
},
),
}
cache.keyer = newLeaseKeyer(locator, cache.countErr)
return cache
}
// Describe is used to describe Prometheus metrics.
func (c *DiskCache) Describe(descs chan<- *prometheus.Desc) {
prometheus.DescribeByCollect(c, descs)
}
// Collect is used to collect Prometheus metrics.
func (c *DiskCache) Collect(metrics chan<- prometheus.Metric) {
c.requestTotals.Collect(metrics)
c.missTotals.Collect(metrics)
c.bytesStoredtotals.Collect(metrics)
c.bytesFetchedtotals.Collect(metrics)
c.bytesLoserTotals.Collect(metrics)
c.errTotal.Collect(metrics)
c.walkerRemovalTotal.Collect(metrics)
c.walkerErrorTotal.Collect(metrics)
c.walkerEmptyDirTotal.Collect(metrics)
c.walkerEmptyDirRemovalTotal.Collect(metrics)
}
func (c *DiskCache) countErr(err error) error {
switch err {
case ErrMissingLeaseFile:
c.errTotal.WithLabelValues("ErrMissingLeaseFile").Inc()
case ErrPendingExists:
c.errTotal.WithLabelValues("ErrPendingExists").Inc()
}
return err
}
// ErrReqNotFound indicates the request does not exist within the repo digest
var ErrReqNotFound = errors.New("request digest not found within repo namespace")
// GetStream will fetch the cached stream for a request. It is the
// responsibility of the caller to close the stream when done.
func (c *DiskCache) GetStream(ctx context.Context, repo *gitalypb.Repository, req proto.Message) (_ io.ReadCloser, err error) {
defer func() {
if err != nil {
c.missTotals.Inc()
}
}()
c.requestTotals.Inc()
respPath, err := c.KeyPath(ctx, repo, req)
switch {
case os.IsNotExist(err):
return nil, ErrReqNotFound
case err == nil:
break
default:
return nil, err
}
ctxlogrus.Extract(ctx).
WithField("stream_path", respPath).
Info("getting stream")
respF, err := os.Open(respPath)
switch {
case os.IsNotExist(err):
return nil, ErrReqNotFound
case err == nil:
break
default:
return nil, err
}
return instrumentedReadCloser{
ReadCloser: respF,
counter: c.bytesFetchedtotals,
}, nil
}
type instrumentedReadCloser struct {
io.ReadCloser
counter prometheus.Counter
}
func (irc instrumentedReadCloser) Read(p []byte) (n int, err error) {
n, err = irc.ReadCloser.Read(p)
irc.counter.Add(float64(n))
return
}
// PutStream will store a stream in a repo-namespace keyed by the digest of the
// request protobuf message.
func (c *DiskCache) PutStream(ctx context.Context, repo *gitalypb.Repository, req proto.Message, src io.Reader) error {
reqPath, err := c.KeyPath(ctx, repo, req)
if err != nil {
return err
}
ctxlogrus.Extract(ctx).
WithField("stream_path", reqPath).
Info("putting stream")
var n int64
isWinner := c.af.trackFile(reqPath)
defer func() {
if !isWinner() {
c.bytesLoserTotals.Add(float64(n))
}
}()
if err := os.MkdirAll(filepath.Dir(reqPath), 0o755); err != nil {
return err
}
sf, err := safe.NewFileWriter(reqPath)
if err != nil {
return err
}
defer sf.Close()
n, err = io.Copy(sf, src)
if err != nil {
return err
}
c.bytesStoredtotals.Add(float64(n))
if err := sf.Commit(); err != nil {
c.errTotal.WithLabelValues("ErrSafefileCommit").Inc()
return err
}
return nil
}
// KeyPath returns the cache path for the given request.
func (c *DiskCache) KeyPath(ctx context.Context, repo *gitalypb.Repository, req proto.Message) (string, error) {
return c.keyer.keyPath(ctx, repo, req)
}
// StartLease will mark the repository as being in an indeterministic state. This is typically used
// when modifying the repo, since the cache is not stable until after the modification is complete.
// A lease object will be returned that allows the caller to signal the end of the lease.
func (c *DiskCache) StartLease(repo *gitalypb.Repository) (LeaseEnder, error) {
pendingPath, err := c.keyer.newPendingLease(repo)
if err != nil {
return lease{}, err
}
return lease{
pendingPath: pendingPath,
repo: repo,
keyer: c.keyer,
countErr: c.countErr,
}, nil
}
type lease struct {
pendingPath string
repo *gitalypb.Repository
keyer leaseKeyer
countErr func(error) error
}
// EndLease will end the lease by removing the pending lease file and updating
// the key file with the current lease ID.
func (l lease) EndLease(ctx context.Context) error {
_, err := l.keyer.updateLatest(ctx, l.repo)
if err != nil {
return err
}
if err := os.Remove(l.pendingPath); err != nil {
if os.IsNotExist(err) {
return l.countErr(ErrMissingLeaseFile)
}
return err
}
return nil
}
|