stringpool/stringpool.go

   1 // stringpool provides a pool of string pointers, ensuring that each string is
   2 // stored only once in memory. This is useful for queries that have many
   3 // results, as the amount of source packages is limited. So, as soon as
   4 // len(results) > len(sourcepackages), you save memory using a stringpool.
   5 package stringpool
   6
   7 import (
   8         "sync"
   9 )
  10
  11 type StringPool struct {
  12         sync.RWMutex
  13         strings map[string]*string
  14 }
  15
  16 func NewStringPool() *StringPool {
  17         return &StringPool{
  18                 strings: make(map[string]*string)}
  19 }
  20
  21 func (pool *StringPool) Get(s string) *string {
  22         // Check if the entry is already in the pool with a slightly cheaper
  23         // (read-only) mutex.
  24         pool.RLock()
  25         stored, ok := pool.strings[s]
  26         pool.RUnlock()
  27         if ok {
  28                 return stored
  29         }
  30
  31         pool.Lock()
  32         defer pool.Unlock()
  33         stored, ok = pool.strings[s]
  34         if ok {
  35                 return stored
  36         }
  37         pool.strings[s] = &s
  38         return &s
  39 }