implement DB connections pooling to mitigate blocking nature of mattn/sqlite3

1 files changed, 42 insertions, 0 deletions

diff --git a/pool.go b/pool.go
new file mode 100644
index 0000000..06e355c
--- /dev/null
+++ b/pool.go
@@ -0,0 +1,42 @@
+package main
+
+import (
+	"sync"
+)
+
+const MAX_POOL_SIZE = 50
+
+// Pool is a simple pool implementation which grows (up to MAX_POOL_SIZE) when
+// needed.
+type Pool[T any] struct {
+	New func() (*T, error)
+	pool [MAX_POOL_SIZE]*T
+	size int8
+	mu sync.Mutex
+}
+
+// Get returns an instance of T from the pool if it's has one. When it doesn't
+// - a new instance is created and returned.
+func (p *Pool[T]) Get() (*T, error) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	last := p.size - 1
+	if last < 0 {
+		return p.New()
+	}
+	res := p.pool[last]
+	p.pool[last] = nil
+	p.size = last
+	return res, nil
+}
+
+// Put returns an instance of T to the pool. If the pool is full - does nothing.
+func (p *Pool[T]) Put(item *T) {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.size + 1 > MAX_POOL_SIZE {
+		return
+	}
+	p.pool[p.size] = item
+	p.size = p.size + 1
+}