frostfs-node/pkg/local_object_storage/writecache/mode.go

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package writecache
import (
"errors"
"fmt"
"time"
"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard/mode"
)
// ErrReadOnly is returned when Put/Write is performed in a read-only mode.
var ErrReadOnly = errors.New("write-cache is in read-only mode")
// SetMode sets write-cache mode of operation.
// When shard is put in read-only mode all objects in memory are flushed to disk
// and all background jobs are suspended.
func (c *cache) SetMode(m mode.Mode) error {
c.modeMtx.Lock()
defer c.modeMtx.Unlock()
if m.ReadOnly() == c.readOnly() {
c.mode = m
return nil
}
if c.db != nil {
if err := c.db.Close(); err != nil {
return fmt.Errorf("can't close write-cache database: %w", err)
}
c.db = nil
}
// Suspend producers to ensure there are channel send operations in fly.
// flushCh is populated by `flush` with `modeMtx` taken, thus waiting until it is empty
// guarantees that there are no in-fly operations.
for len(c.flushCh) != 0 {
c.log.Info("waiting for channels to flush")
time.Sleep(time.Second)
}
if err := c.openStore(m.ReadOnly()); err != nil {
return err
}
c.mode = m
return nil
}
// readOnly returns true if current mode is read-only.
// `c.modeMtx` must be taken.
func (c *cache) readOnly() bool {
return c.mode.ReadOnly()
}