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ensure the stats is always 64bit aligned 

The first word in an allocated struct can be relied upon to be
64-bit aligned. Refer to https://pkg.go.dev/sync/atomic#pkg-note-BUG.

Signed-off-by: Benjamin Wang <wachao@vmware.com>
pull/584/head
Benjamin Wang 2023-10-23 13:13:18 +01:00
parent 233156a53a
commit 26f89a5951
1 changed files with 12 additions and 3 deletions
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15
db.go
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@ -36,6 +36,12 @@ const (
// All data access is performed through transactions which can be obtained through the DB. // All data access is performed through transactions which can be obtained through the DB.
// All the functions on DB will return a ErrDatabaseNotOpen if accessed before Open() is called. // All the functions on DB will return a ErrDatabaseNotOpen if accessed before Open() is called.
type DB struct { type DB struct {
// Put `stats` at the first field to ensure it's 64-bit aligned. Note that
// the first word in an allocated struct can be relied upon to be 64-bit
// aligned. Refer to https://pkg.go.dev/sync/atomic#pkg-note-BUG. Also
// refer to discussion in https://github.com/etcd-io/bbolt/issues/577.
stats Stats
// When enabled, the database will perform a Check() after every commit. // When enabled, the database will perform a Check() after every commit.
// A panic is issued if the database is in an inconsistent state. This // A panic is issued if the database is in an inconsistent state. This
// flag has a large performance impact so it should only be used for // flag has a large performance impact so it should only be used for
@ -125,7 +131,6 @@ type DB struct {
opened bool opened bool
rwtx *Tx rwtx *Tx
txs []*Tx txs []*Tx
stats Stats
freelist *freelist freelist *freelist
freelistLoad sync.Once freelistLoad sync.Once
@ -1275,6 +1280,12 @@ var DefaultOptions = &Options{
// Stats represents statistics about the database. // Stats represents statistics about the database.
type Stats struct { type Stats struct {
// Put `TxStats` at the first field to ensure it's 64-bit aligned. Note
// that the first word in an allocated struct can be relied upon to be
// 64-bit aligned. Refer to https://pkg.go.dev/sync/atomic#pkg-note-BUG.
// Also refer to discussion in https://github.com/etcd-io/bbolt/issues/577.
TxStats TxStats // global, ongoing stats.
// Freelist stats // Freelist stats
FreePageN int // total number of free pages on the freelist FreePageN int // total number of free pages on the freelist
PendingPageN int // total number of pending pages on the freelist PendingPageN int // total number of pending pages on the freelist
@ -1284,8 +1295,6 @@ type Stats struct {
// Transaction stats // Transaction stats
TxN int // total number of started read transactions TxN int // total number of started read transactions
OpenTxN int // number of currently open read transactions OpenTxN int // number of currently open read transactions
TxStats TxStats // global, ongoing stats.
} }
// Sub calculates and returns the difference between two sets of database stats. // Sub calculates and returns the difference between two sets of database stats.