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lock around read operations in graph

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Writes and reads will fail with ErrBusy if there's
concurrent reads or writes, respectively. It is
not sufficient to only lock around writes.
This commit is contained in:
Daniel Norberg 2013-11-05 18:26:07 -05:00
parent 980eda4c25
commit 1dc34e2b96
1 changed files with 23 additions and 1 deletions
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24
gograph/gograph.go
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@ -138,7 +138,14 @@ func (db *Database) Set(fullPath, id string) (*Entity, error) {
// Return true if a name already exists in the database
func (db *Database) Exists(name string) bool {
return db.Get(name) != nil
db.mux.Lock()
defer db.mux.Unlock()
e, err := db.get(name)
if err != nil {
return false
}
return e != nil
}
func (db *Database) setEdge(parentPath, name string, e *Entity) error {
@ -165,6 +172,9 @@ func (db *Database) RootEntity() *Entity {
// Return the entity for a given path
func (db *Database) Get(name string) *Entity {
db.mux.Lock()
defer db.mux.Unlock()
e, err := db.get(name)
if err != nil {
return nil
@ -200,6 +210,9 @@ func (db *Database) get(name string) (*Entity, error) {
// List all entities by from the name
// The key will be the full path of the entity
func (db *Database) List(name string, depth int) Entities {
db.mux.Lock()
defer db.mux.Unlock()
out := Entities{}
e, err := db.get(name)
if err != nil {
@ -212,6 +225,9 @@ func (db *Database) List(name string, depth int) Entities {
}
func (db *Database) Walk(name string, walkFunc WalkFunc, depth int) error {
db.mux.Lock()
defer db.mux.Unlock()
e, err := db.get(name)
if err != nil {
return err
@ -226,6 +242,9 @@ func (db *Database) Walk(name string, walkFunc WalkFunc, depth int) error {
// Return the refrence count for a specified id
func (db *Database) Refs(id string) int {
db.mux.Lock()
defer db.mux.Unlock()
var count int
if err := db.conn.QueryRow("SELECT COUNT(*) FROM edge WHERE entity_id = ?;", id).Scan(&count); err != nil {
return 0
@ -235,6 +254,9 @@ func (db *Database) Refs(id string) int {
// Return all the id's path references
func (db *Database) RefPaths(id string) Edges {
db.mux.Lock()
defer db.mux.Unlock()
refs := Edges{}
rows, err := db.conn.Query("SELECT name, parent_id FROM edge WHERE entity_id = ?;", id)