1 files changed, 112 insertions, 0 deletions
diff --git a/vendor/github.com/jackc/pgx/v5/internal/stmtcache/lru_cache.go b/vendor/github.com/jackc/pgx/v5/internal/stmtcache/lru_cache.go
new file mode 100644
index 0000000..dec83f4
--- /dev/null
+++ b/vendor/github.com/jackc/pgx/v5/internal/stmtcache/lru_cache.go
@@ -0,0 +1,112 @@
+package stmtcache
+
+import (
+	"container/list"
+
+	"github.com/jackc/pgx/v5/pgconn"
+)
+
+// LRUCache implements Cache with a Least Recently Used (LRU) cache.
+type LRUCache struct {
+	cap          int
+	m            map[string]*list.Element
+	l            *list.List
+	invalidStmts []*pgconn.StatementDescription
+}
+
+// NewLRUCache creates a new LRUCache. cap is the maximum size of the cache.
+func NewLRUCache(cap int) *LRUCache {
+	return &LRUCache{
+		cap: cap,
+		m:   make(map[string]*list.Element),
+		l:   list.New(),
+	}
+}
+
+// Get returns the statement description for sql. Returns nil if not found.
+func (c *LRUCache) Get(key string) *pgconn.StatementDescription {
+	if el, ok := c.m[key]; ok {
+		c.l.MoveToFront(el)
+		return el.Value.(*pgconn.StatementDescription)
+	}
+
+	return nil
+
+}
+
+// Put stores sd in the cache. Put panics if sd.SQL is "". Put does nothing if sd.SQL already exists in the cache or
+// sd.SQL has been invalidated and HandleInvalidated has not been called yet.
+func (c *LRUCache) Put(sd *pgconn.StatementDescription) {
+	if sd.SQL == "" {
+		panic("cannot store statement description with empty SQL")
+	}
+
+	if _, present := c.m[sd.SQL]; present {
+		return
+	}
+
+	// The statement may have been invalidated but not yet handled. Do not readd it to the cache.
+	for _, invalidSD := range c.invalidStmts {
+		if invalidSD.SQL == sd.SQL {
+			return
+		}
+	}
+
+	if c.l.Len() == c.cap {
+		c.invalidateOldest()
+	}
+
+	el := c.l.PushFront(sd)
+	c.m[sd.SQL] = el
+}
+
+// Invalidate invalidates statement description identified by sql. Does nothing if not found.
+func (c *LRUCache) Invalidate(sql string) {
+	if el, ok := c.m[sql]; ok {
+		delete(c.m, sql)
+		c.invalidStmts = append(c.invalidStmts, el.Value.(*pgconn.StatementDescription))
+		c.l.Remove(el)
+	}
+}
+
+// InvalidateAll invalidates all statement descriptions.
+func (c *LRUCache) InvalidateAll() {
+	el := c.l.Front()
+	for el != nil {
+		c.invalidStmts = append(c.invalidStmts, el.Value.(*pgconn.StatementDescription))
+		el = el.Next()
+	}
+
+	c.m = make(map[string]*list.Element)
+	c.l = list.New()
+}
+
+// GetInvalidated returns a slice of all statement descriptions invalidated since the last call to RemoveInvalidated.
+func (c *LRUCache) GetInvalidated() []*pgconn.StatementDescription {
+	return c.invalidStmts
+}
+
+// RemoveInvalidated removes all invalidated statement descriptions. No other calls to Cache must be made between a
+// call to GetInvalidated and RemoveInvalidated or RemoveInvalidated may remove statement descriptions that were
+// never seen by the call to GetInvalidated.
+func (c *LRUCache) RemoveInvalidated() {
+	c.invalidStmts = nil
+}
+
+// Len returns the number of cached prepared statement descriptions.
+func (c *LRUCache) Len() int {
+	return c.l.Len()
+}
+
+// Cap returns the maximum number of cached prepared statement descriptions.
+func (c *LRUCache) Cap() int {
+	return c.cap
+}
+
+func (c *LRUCache) invalidateOldest() {
+	oldest := c.l.Back()
+	sd := oldest.Value.(*pgconn.StatementDescription)
+	c.invalidStmts = append(c.invalidStmts, sd)
+	delete(c.m, sd.SQL)
+	c.l.Remove(oldest)
+}