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sqlite-storage.go
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sqlite-storage.go
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package sqliteStorage
import (
"bytes"
"context"
"errors"
"expvar"
"fmt"
"io"
"log"
"net/url"
"os"
"runtime"
"runtime/pprof"
"strings"
"sync"
"time"
"crawshaw.io/sqlite"
"crawshaw.io/sqlite/sqlitex"
"github.com/anacrolix/missinggo/iter"
"github.com/anacrolix/missinggo/v2/resource"
"github.com/anacrolix/torrent/storage"
)
type conn = *sqlite.Conn
func initConn(conn conn, opts ProviderOpts) error {
// Recursive triggers are required because we need to trim the blob_meta size after trimming to
// capacity. Hopefully we don't hit the recursion limit, and if we do, there's an error thrown.
err := sqlitex.ExecTransient(conn, "pragma recursive_triggers=on", nil)
if err != nil {
return err
}
err = sqlitex.ExecTransient(conn, `pragma synchronous=off`, nil)
if err != nil {
return err
}
if opts.NoConcurrentBlobReads {
err = sqlitex.ExecTransient(conn, `pragma journal_mode=off`, nil)
if err != nil {
return err
}
}
if opts.MmapSizeOk {
err = sqlitex.ExecTransient(conn, fmt.Sprintf(`pragma mmap_size=%d`, opts.MmapSize), nil)
if err != nil {
return err
}
}
return nil
}
func InitSchema(conn conn, pageSize int, triggers bool) error {
if pageSize != 0 {
err := sqlitex.ExecScript(conn, fmt.Sprintf("pragma page_size=%d", pageSize))
if err != nil {
return err
}
}
err := sqlitex.ExecScript(conn, `
-- We have to opt into this before creating any tables, or before a vacuum to enable it. It means we
-- can trim the database file size with partial vacuums without having to do a full vacuum, which
-- locks everything.
pragma auto_vacuum=incremental;
create table if not exists blob (
name text,
last_used timestamp default (datetime('now')),
data blob,
primary key (name)
);
create table if not exists blob_meta (
key text primary key,
value
);
create index if not exists blob_last_used on blob(last_used);
-- While sqlite *seems* to be faster to get sum(length(data)) instead of
-- sum(length(data)), it may still require a large table scan at start-up or with a
-- cold-cache. With this we can be assured that it doesn't.
insert or ignore into blob_meta values ('size', 0);
create table if not exists setting (
name primary key on conflict replace,
value
);
create view if not exists deletable_blob as
with recursive excess (
usage_with,
last_used,
blob_rowid,
data_length
) as (
select *
from (
select
(select value from blob_meta where key='size') as usage_with,
last_used,
rowid,
length(data)
from blob order by last_used, rowid limit 1
)
where usage_with > (select value from setting where name='capacity')
union all
select
usage_with-data_length as new_usage_with,
blob.last_used,
blob.rowid,
length(data)
from excess join blob
on blob.rowid=(select rowid from blob where (last_used, rowid) > (excess.last_used, blob_rowid))
where new_usage_with > (select value from setting where name='capacity')
)
select * from excess;
`)
if err != nil {
return err
}
if triggers {
err := sqlitex.ExecScript(conn, `
create trigger if not exists after_insert_blob
after insert on blob
begin
update blob_meta set value=value+length(cast(new.data as blob)) where key='size';
delete from blob where rowid in (select blob_rowid from deletable_blob);
end;
create trigger if not exists after_update_blob
after update of data on blob
begin
update blob_meta set value=value+length(cast(new.data as blob))-length(cast(old.data as blob)) where key='size';
delete from blob where rowid in (select blob_rowid from deletable_blob);
end;
create trigger if not exists after_delete_blob
after delete on blob
begin
update blob_meta set value=value-length(cast(old.data as blob)) where key='size';
end;
`)
if err != nil {
return err
}
}
return nil
}
type NewPiecesStorageOpts struct {
NewPoolOpts
ProvOpts func(*ProviderOpts)
StorageOpts func(*storage.ResourcePiecesOpts)
}
// A convenience function that creates a connection pool, resource provider, and a pieces storage
// ClientImpl and returns them all with a Close attached.
func NewPiecesStorage(opts NewPiecesStorageOpts) (_ storage.ClientImplCloser, err error) {
conns, provOpts, err := NewPool(opts.NewPoolOpts)
if err != nil {
return
}
if f := opts.ProvOpts; f != nil {
f(&provOpts)
}
prov, err := NewProvider(conns, provOpts)
if err != nil {
conns.Close()
return
}
storageOpts := storage.ResourcePiecesOpts{
NoSizedPuts: provOpts.NoConcurrentBlobReads,
}
if f := opts.StorageOpts; f != nil {
f(&storageOpts)
}
store := storage.NewResourcePiecesOpts(prov, storageOpts)
return struct {
storage.ClientImpl
io.Closer
}{
store,
prov,
}, nil
}
type NewPoolOpts struct {
// See https://www.sqlite.org/c3ref/open.html. NB: "If the filename is an empty string, then a
// private, temporary on-disk database will be created. This private database will be
// automatically deleted as soon as the database connection is closed."
Path string
Memory bool
NumConns int
// Forces WAL, disables shared caching.
NoConcurrentBlobReads bool
DontInitSchema bool
PageSize int
// If non-zero, overrides the existing setting.
Capacity int64
}
// There's some overlap here with NewPoolOpts, and I haven't decided what needs to be done. For now,
// the fact that the pool opts are a superset, means our helper NewPiecesStorage can just take the
// top-level option type.
type ProviderOpts struct {
NumConns int
// Concurrent blob reads require WAL.
NoConcurrentBlobReads bool
BatchWrites bool
MmapSize int64
MmapSizeOk bool
}
// Remove any capacity limits.
func UnlimitCapacity(conn conn) error {
return sqlitex.Exec(conn, "delete from setting where key='capacity'", nil)
}
// Set the capacity limit to exactly this value.
func SetCapacity(conn conn, cap int64) error {
return sqlitex.Exec(conn, "insert into setting values ('capacity', ?)", nil, cap)
}
func NewPool(opts NewPoolOpts) (_ ConnPool, _ ProviderOpts, err error) {
if opts.NumConns == 0 {
opts.NumConns = runtime.NumCPU()
}
path := url.PathEscape(opts.Path)
if opts.Memory {
path = ":memory:"
}
values := make(url.Values)
if opts.NoConcurrentBlobReads || opts.Memory {
values.Add("cache", "shared")
}
uri := fmt.Sprintf("file:%s?%s", path, values.Encode())
conns, err := func() (ConnPool, error) {
switch opts.NumConns {
case 1:
conn, err := sqlite.OpenConn(uri, 0)
return &poolFromConn{conn: conn}, err
default:
return sqlitex.Open(uri, 0, opts.NumConns)
}
}()
if err != nil {
return
}
defer func() {
if err != nil {
conns.Close()
}
}()
conn := conns.Get(context.TODO())
defer conns.Put(conn)
if !opts.DontInitSchema {
if opts.PageSize == 0 {
opts.PageSize = 1 << 14
}
err = InitSchema(conn, opts.PageSize, true)
if err != nil {
return
}
}
if opts.Capacity != 0 {
err = SetCapacity(conn, opts.Capacity)
if err != nil {
return
}
}
return conns, ProviderOpts{
NumConns: opts.NumConns,
NoConcurrentBlobReads: opts.NoConcurrentBlobReads || opts.Memory || opts.NumConns == 1,
BatchWrites: opts.NumConns > 1,
MmapSize: 1 << 23, // 8 MiB
MmapSizeOk: true,
}, nil
}
// Emulates a ConnPool from a single Conn. Might be faster than using a sqlitex.Pool.
type poolFromConn struct {
mu sync.Mutex
conn conn
}
func (me *poolFromConn) Get(ctx context.Context) conn {
me.mu.Lock()
return me.conn
}
func (me *poolFromConn) Put(conn conn) {
if conn != me.conn {
panic("expected to same conn")
}
me.mu.Unlock()
}
func (me *poolFromConn) Close() error {
return me.conn.Close()
}
// Needs the ConnPool size so it can initialize all the connections with pragmas. Takes ownership of
// the ConnPool (since it has to initialize all the connections anyway).
func NewProvider(pool ConnPool, opts ProviderOpts) (_ *provider, err error) {
_, err = initPoolConns(context.TODO(), pool, opts)
if err != nil {
err = fmt.Errorf("initing pool conns: %w", err)
return
}
prov := &provider{pool: pool, opts: opts}
if opts.BatchWrites {
if opts.NumConns < 2 {
err = errors.New("batch writes requires more than 1 conn")
return
}
writes := make(chan writeRequest)
prov.writes = writes
// This is retained for backwards compatibility. It may not be necessary.
runtime.SetFinalizer(prov, func(p *provider) {
p.Close()
})
go providerWriter(writes, prov.pool)
}
return prov, nil
}
func initPoolConns(ctx context.Context, pool ConnPool, opts ProviderOpts) (numInited int, err error) {
var conns []conn
defer func() {
for _, c := range conns {
pool.Put(c)
}
}()
for range iter.N(opts.NumConns) {
conn := pool.Get(ctx)
if conn == nil {
break
}
conns = append(conns, conn)
err = initConn(conn, opts)
if err != nil {
err = fmt.Errorf("initing conn %v: %w", len(conns), err)
return
}
numInited++
}
return
}
type ConnPool interface {
Get(context.Context) conn
Put(conn)
Close() error
}
type provider struct {
pool ConnPool
writes chan<- writeRequest
opts ProviderOpts
closeMu sync.RWMutex
closed bool
closeErr error
}
var _ storage.ConsecutiveChunkReader = (*provider)(nil)
func (p *provider) ReadConsecutiveChunks(prefix string) (io.ReadCloser, error) {
p.closeMu.RLock()
runner, err := p.getReadWithConnRunner()
if err != nil {
p.closeMu.RUnlock()
return nil, err
}
r, w := io.Pipe()
go func() {
defer p.closeMu.RUnlock()
err = runner(func(_ context.Context, conn conn) error {
var written int64
err = sqlitex.Exec(conn, `
select
data,
cast(substr(name, ?+1) as integer) as offset
from blob
where name like ?||'%'
order by offset`,
func(stmt *sqlite.Stmt) error {
offset := stmt.ColumnInt64(1)
if offset != written {
return fmt.Errorf("got chunk at offset %v, expected offset %v", offset, written)
}
// TODO: Avoid intermediate buffers here
r := stmt.ColumnReader(0)
w1, err := io.Copy(w, r)
written += w1
return err
},
len(prefix),
prefix,
)
return err
})
w.CloseWithError(err)
}()
return r, nil
}
func (me *provider) Close() error {
me.closeMu.Lock()
defer me.closeMu.Unlock()
if me.closed {
return me.closeErr
}
if me.writes != nil {
close(me.writes)
}
me.closeErr = me.pool.Close()
me.closed = true
return me.closeErr
}
type writeRequest struct {
query withConn
done chan<- error
labels pprof.LabelSet
}
var expvars = expvar.NewMap("sqliteStorage")
func runQueryWithLabels(query withConn, labels pprof.LabelSet, conn conn) (err error) {
pprof.Do(context.Background(), labels, func(ctx context.Context) {
// We pass in the context in the hope that the CPU profiler might incorporate sqlite
// activity the action that triggered it. It doesn't seem that way, since those calls don't
// take a context.Context themselves. It may come in useful in the goroutine profiles
// though, and doesn't hurt to expose it here for other purposes should things change.
err = query(ctx, conn)
})
return
}
// Intentionally avoids holding a reference to *provider to allow it to use a finalizer, and to have
// stronger typing on the writes channel.
func providerWriter(writes <-chan writeRequest, pool ConnPool) {
conn := pool.Get(context.TODO())
if conn == nil {
return
}
defer pool.Put(conn)
for {
first, ok := <-writes
if !ok {
return
}
var buf []func()
var cantFail error
func() {
defer sqlitex.Save(conn)(&cantFail)
firstErr := runQueryWithLabels(first.query, first.labels, conn)
buf = append(buf, func() { first.done <- firstErr })
for {
select {
case wr, ok := <-writes:
if ok {
err := runQueryWithLabels(wr.query, wr.labels, conn)
buf = append(buf, func() { wr.done <- err })
continue
}
default:
}
break
}
}()
// Not sure what to do if this failed.
if cantFail != nil {
expvars.Add("batchTransactionErrors", 1)
}
// Signal done after we know the transaction succeeded.
for _, done := range buf {
done()
}
expvars.Add("batchTransactions", 1)
expvars.Add("batchedQueries", int64(len(buf)))
//log.Printf("batched %v write queries", len(buf))
}
}
func (p *provider) NewInstance(s string) (resource.Instance, error) {
return instance{s, p}, nil
}
type instance struct {
location string
p *provider
}
func getLabels(skip int) pprof.LabelSet {
return pprof.Labels("sqlite-storage-action", func() string {
var pcs [8]uintptr
runtime.Callers(skip+3, pcs[:])
fs := runtime.CallersFrames(pcs[:])
f, _ := fs.Next()
funcName := f.Func.Name()
funcName = funcName[strings.LastIndexByte(funcName, '.')+1:]
//log.Printf("func name: %q", funcName)
return funcName
}())
}
func (p *provider) withConn(with withConn, write bool, skip int) error {
p.closeMu.RLock()
// I think we need to check this here because it may not be valid to send to the writes channel
// if we're already closed. So don't try to move this check into getReadWithConnRunner.
if p.closed {
p.closeMu.RUnlock()
return errors.New("closed")
}
if write && p.opts.BatchWrites {
done := make(chan error)
p.writes <- writeRequest{
query: with,
done: done,
labels: getLabels(skip + 1),
}
p.closeMu.RUnlock()
return <-done
} else {
defer p.closeMu.RUnlock()
runner, err := p.getReadWithConnRunner()
if err != nil {
return err
}
return runner(with)
}
}
// Obtains a DB conn and returns a withConn for executing with it. If no error is returned from this
// function, the runner *must* be used or the conn is leaked. You should check the provider isn't
// closed before using this.
func (p *provider) getReadWithConnRunner() (with func(withConn) error, err error) {
conn := p.pool.Get(context.TODO())
if conn == nil {
err = errors.New("couldn't get pool conn")
return
}
with = func(with withConn) error {
defer p.pool.Put(conn)
return runQueryWithLabels(with, getLabels(1), conn)
}
return
}
type withConn func(context.Context, conn) error
func (i instance) withConn(with withConn, write bool) error {
return i.p.withConn(with, write, 1)
}
func (i instance) getConn() *sqlite.Conn {
return i.p.pool.Get(context.TODO())
}
func (i instance) putConn(conn *sqlite.Conn) {
i.p.pool.Put(conn)
}
func (i instance) Readdirnames() (names []string, err error) {
prefix := i.location + "/"
err = i.withConn(func(_ context.Context, conn conn) error {
return sqlitex.Exec(conn, "select name from blob where name like ?", func(stmt *sqlite.Stmt) error {
names = append(names, stmt.ColumnText(0)[len(prefix):])
return nil
}, prefix+"%")
}, false)
//log.Printf("readdir %q gave %q", i.location, names)
return
}
func (i instance) getBlobRowid(conn conn) (rowid int64, err error) {
rows := 0
err = sqlitex.Exec(conn, "select rowid from blob where name=?", func(stmt *sqlite.Stmt) error {
rowid = stmt.ColumnInt64(0)
rows++
return nil
}, i.location)
if err != nil {
return
}
if rows == 1 {
return
}
if rows == 0 {
err = errors.New("blob not found")
return
}
panic(rows)
}
type connBlob struct {
*sqlite.Blob
onClose func()
}
func (me connBlob) Close() error {
err := me.Blob.Close()
me.onClose()
return err
}
func (i instance) Get() (ret io.ReadCloser, err error) {
conn := i.getConn()
if conn == nil {
panic("nil sqlite conn")
}
blob, err := i.openBlob(conn, false, true)
if err != nil {
i.putConn(conn)
return
}
var once sync.Once
return connBlob{blob, func() {
once.Do(func() { i.putConn(conn) })
}}, nil
}
func (i instance) openBlob(conn conn, write, updateAccess bool) (*sqlite.Blob, error) {
rowid, err := i.getBlobRowid(conn)
if err != nil {
return nil, err
}
// This seems to cause locking issues with in-memory databases. Is it something to do with not
// having WAL?
if updateAccess {
err = sqlitex.Exec(conn, "update blob set last_used=datetime('now') where rowid=?", nil, rowid)
if err != nil {
err = fmt.Errorf("updating last_used: %w", err)
return nil, err
}
if conn.Changes() != 1 {
panic(conn.Changes())
}
}
return conn.OpenBlob("main", "blob", "data", rowid, write)
}
func (i instance) PutSized(reader io.Reader, size int64) (err error) {
err = i.withConn(func(_ context.Context, conn conn) error {
err := sqlitex.Exec(conn, "insert or replace into blob(name, data) values(?, zeroblob(?))",
nil,
i.location, size)
if err != nil {
return err
}
blob, err := i.openBlob(conn, true, false)
if err != nil {
return err
}
defer blob.Close()
_, err = io.Copy(blob, reader)
return err
}, true)
return
}
func (i instance) Put(reader io.Reader) (err error) {
var buf bytes.Buffer
_, err = io.Copy(&buf, reader)
if err != nil {
return err
}
if false {
return i.PutSized(&buf, int64(buf.Len()))
} else {
return i.withConn(func(_ context.Context, conn conn) error {
for range iter.N(10) {
err = sqlitex.Exec(conn,
"insert or replace into blob(name, data) values(?, cast(? as blob))",
nil,
i.location, buf.Bytes())
if err, ok := err.(sqlite.Error); ok && err.Code == sqlite.SQLITE_BUSY {
log.Print("sqlite busy")
time.Sleep(time.Second)
continue
}
break
}
return err
}, true)
}
}
type fileInfo struct {
size int64
}
func (f fileInfo) Name() string {
panic("implement me")
}
func (f fileInfo) Size() int64 {
return f.size
}
func (f fileInfo) Mode() os.FileMode {
panic("implement me")
}
func (f fileInfo) ModTime() time.Time {
panic("implement me")
}
func (f fileInfo) IsDir() bool {
panic("implement me")
}
func (f fileInfo) Sys() interface{} {
panic("implement me")
}
func (i instance) Stat() (ret os.FileInfo, err error) {
err = i.withConn(func(_ context.Context, conn conn) error {
var blob *sqlite.Blob
blob, err = i.openBlob(conn, false, false)
if err != nil {
return err
}
defer blob.Close()
ret = fileInfo{blob.Size()}
return nil
}, false)
return
}
func (i instance) ReadAt(p []byte, off int64) (n int, err error) {
err = i.withConn(func(_ context.Context, conn conn) error {
if false {
var blob *sqlite.Blob
blob, err = i.openBlob(conn, false, true)
if err != nil {
return err
}
defer blob.Close()
if off >= blob.Size() {
err = io.EOF
return err
}
if off+int64(len(p)) > blob.Size() {
p = p[:blob.Size()-off]
}
n, err = blob.ReadAt(p, off)
} else {
gotRow := false
err = sqlitex.Exec(
conn,
"select substr(data, ?, ?) from blob where name=?",
func(stmt *sqlite.Stmt) error {
if gotRow {
panic("found multiple matching blobs")
} else {
gotRow = true
}
n = stmt.ColumnBytes(0, p)
return nil
},
off+1, len(p), i.location,
)
if err != nil {
return err
}
if !gotRow {
err = errors.New("blob not found")
return err
}
if n < len(p) {
err = io.EOF
}
}
return nil
}, false)
return
}
func (i instance) WriteAt(bytes []byte, i2 int64) (int, error) {
panic("implement me")
}
func (i instance) Delete() error {
return i.withConn(func(_ context.Context, conn conn) error {
return sqlitex.Exec(conn, "delete from blob where name=?", nil, i.location)
}, true)
}