86 lines
1.5 KiB
Go
86 lines
1.5 KiB
Go
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package sqladapter
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import (
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"database/sql"
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"errors"
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"sync"
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"sync/atomic"
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)
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var (
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activeStatements int64
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)
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// Stmt represents a *sql.Stmt that is cached and provides the
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// OnEvict method to allow it to clean after itself.
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type Stmt struct {
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*sql.Stmt
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query string
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mu sync.Mutex
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count int64
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dead bool
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}
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// NewStatement creates an returns an opened statement
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func NewStatement(stmt *sql.Stmt, query string) *Stmt {
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s := &Stmt{
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Stmt: stmt,
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query: query,
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}
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atomic.AddInt64(&activeStatements, 1)
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return s
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}
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// Open marks the statement as in-use
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func (c *Stmt) Open() (*Stmt, error) {
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c.mu.Lock()
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defer c.mu.Unlock()
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if c.dead {
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return nil, errors.New("statement is dead")
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}
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c.count++
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return c, nil
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}
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// Close closes the underlying statement if no other go-routine is using it.
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func (c *Stmt) Close() error {
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c.mu.Lock()
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defer c.mu.Unlock()
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c.count--
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return c.checkClose()
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}
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func (c *Stmt) checkClose() error {
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if c.dead && c.count == 0 {
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// Statement is dead and we can close it for real.
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err := c.Stmt.Close()
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if err != nil {
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return err
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}
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// Reduce active statements counter.
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atomic.AddInt64(&activeStatements, -1)
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}
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return nil
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}
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// OnEvict marks the statement as ready to be cleaned up.
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func (c *Stmt) OnEvict() {
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c.mu.Lock()
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defer c.mu.Unlock()
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c.dead = true
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c.checkClose()
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}
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// NumActiveStatements returns the global number of prepared statements in use
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// at any point.
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func NumActiveStatements() int64 {
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return atomic.LoadInt64(&activeStatements)
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}
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