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lang: funcs: ref: Move reference counting code to a new package

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This also makes it public, although it is designed for internal use
only.
This commit is contained in:
James Shubin
2024-01-22 14:12:46 -05:00
parent 66b826a8e1
commit 28eacdb2bb
4 changed files with 32 additions and 30 deletions
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5
lang/funcs/dage/dage.go
View File

@@ -30,6 +30,7 @@ import (
"github.com/purpleidea/mgmt/engine"
"github.com/purpleidea/mgmt/engine/local"
"github.com/purpleidea/mgmt/lang/funcs/ref"
"github.com/purpleidea/mgmt/lang/funcs/structs"
"github.com/purpleidea/mgmt/lang/interfaces"
"github.com/purpleidea/mgmt/lang/types"
@@ -71,7 +72,7 @@ type Engine struct {
// refCount keeps track of vertex and edge references across the entire
// graph.
refCount *RefCount
refCount *ref.Count
// wgTxn blocks shutdown until the initial Txn has Reversed.
wgTxn *sync.WaitGroup
@@ -161,7 +162,7 @@ func (obj *Engine) Setup() error {
obj.graphMutex = &sync.Mutex{} // TODO: &sync.RWMutex{} ?
obj.tableMutex = &sync.RWMutex{}
obj.refCount = (&RefCount{}).Init()
obj.refCount = (&ref.Count{}).Init()
obj.wgTxn = &sync.WaitGroup{}

5
lang/funcs/dage/txn.go
View File

@@ -24,6 +24,7 @@ import (
"sort"
"sync"
"github.com/purpleidea/mgmt/lang/funcs/ref"
"github.com/purpleidea/mgmt/lang/interfaces"
"github.com/purpleidea/mgmt/pgraph"
)
@@ -41,7 +42,7 @@ const GraphvizDebug = false
// also allows us to change API slightly without re-writing code.
type opapi struct {
GraphAPI interfaces.GraphAPI
RefCount *RefCount
RefCount *ref.Count
}
// opfn is an interface that holds the normal op, and the reverse op if we need
@@ -272,7 +273,7 @@ type graphTxn struct {
// RefCount keeps track of vertex and edge references across the entire
// graph.
RefCount *RefCount
RefCount *ref.Count
// FreeFunc is a function that will get called by a well-behaved user
// when we're done with this Txn.

4
lang/funcs/dage/txn_test.go
View File

@@ -142,7 +142,7 @@ func TestTxn1(t *testing.T) {
GraphAPI: testGraphAPI,
Lock: mutex.Lock,
Unlock: mutex.Unlock,
RefCount: (&RefCount{}).Init(),
RefCount: (&ref.Count{}).Init(),
}
txn := graphTxn.init()
@@ -485,7 +485,7 @@ func TestTxnTable(t *testing.T) {
GraphAPI: testGraphAPI,
Lock: mutex.Lock,
Unlock: mutex.Unlock,
RefCount: (&RefCount{}).Init(),
RefCount: (&ref.Count{}).Init(),
}
txn := graphTxn.init()

48
lang/funcs/dage/ref.go → lang/funcs/ref/ref.go
View File

@@ -15,9 +15,9 @@
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
// Package dage implements a DAG function engine.
// TODO: can we rename this to something more interesting?
package dage
// Package ref implements reference counting for the graph API and function
// engine.
package ref
import (
"fmt"
@@ -27,9 +27,9 @@ import (
"github.com/purpleidea/mgmt/util/errwrap"
)
// RefCount keeps track of vertex and edge references across the entire graph.
// Make sure to lock access somehow, ideally with the provided Locker interface.
type RefCount struct {
// Count keeps track of vertex and edge references across the entire graph. Make
// sure to lock access somehow, ideally with the provided Locker interface.
type Count struct {
// mutex locks this database for read or write.
mutex *sync.Mutex
@@ -37,18 +37,18 @@ type RefCount struct {
vertices map[interfaces.Func]int64
// edges is a reference count of the number of edges used.
edges map[*RefCountEdge]int64 // TODO: hash *RefCountEdge as a key instead
edges map[*CountEdge]int64 // TODO: hash *CountEdge as a key instead
}
// RefCountEdge is a virtual "hash" entry for the RefCount edges map key.
type RefCountEdge struct {
// CountEdge is a virtual "hash" entry for the Count edges map key.
type CountEdge struct {
f1 interfaces.Func
f2 interfaces.Func
arg string
}
// String prints a representation of the references held.
func (obj *RefCount) String() string {
func (obj *Count) String() string {
s := ""
s += fmt.Sprintf("vertices (%d):\n", len(obj.vertices))
for vertex, count := range obj.vertices {
@@ -62,18 +62,18 @@ func (obj *RefCount) String() string {
}
// Init must be called to initialized the struct before first use.
func (obj *RefCount) Init() *RefCount {
func (obj *Count) Init() *Count {
obj.mutex = &sync.Mutex{}
obj.vertices = make(map[interfaces.Func]int64)
obj.edges = make(map[*RefCountEdge]int64)
obj.edges = make(map[*CountEdge]int64)
return obj // return self so it can be called in a chain
}
// Lock the mutex that should be used when reading or writing from this.
func (obj *RefCount) Lock() { obj.mutex.Lock() }
func (obj *Count) Lock() { obj.mutex.Lock() }
// Unlock the mutex that should be used when reading or writing from this.
func (obj *RefCount) Unlock() { obj.mutex.Unlock() }
func (obj *Count) Unlock() { obj.mutex.Unlock() }
// VertexInc increments the reference count for the input vertex. It returns
// true if the reference count for this vertex was previously undefined or zero.
@@ -81,7 +81,7 @@ func (obj *RefCount) Unlock() { obj.mutex.Unlock() }
// to increment a vertex which already has a less than zero count, then this
// will panic. This situation is likely impossible unless someone modified the
// reference counting struct directly.
func (obj *RefCount) VertexInc(f interfaces.Func) bool {
func (obj *Count) VertexInc(f interfaces.Func) bool {
count, _ := obj.vertices[f]
obj.vertices[f] = count + 1
if count == -1 { // unlikely, but catch any bugs
@@ -94,7 +94,7 @@ func (obj *RefCount) VertexInc(f interfaces.Func) bool {
// true if the reference count for this vertex is now zero. True usually means
// we'd want to actually remove this vertex now. If you attempt to decrement a
// vertex which already has a zero count, then this will panic.
func (obj *RefCount) VertexDec(f interfaces.Func) bool {
func (obj *Count) VertexDec(f interfaces.Func) bool {
count, _ := obj.vertices[f]
obj.vertices[f] = count - 1
if count == 0 {
@@ -107,7 +107,7 @@ func (obj *RefCount) VertexDec(f interfaces.Func) bool {
// reference for each arg name in the edge. Since this also increments the
// references for the two input vertices, it returns the corresponding two
// boolean values for these calls. (This function makes two calls to VertexInc.)
func (obj *RefCount) EdgeInc(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (bool, bool) {
func (obj *Count) EdgeInc(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (bool, bool) {
for _, arg := range fe.Args { // ref count each arg
r := obj.makeEdge(f1, f2, arg)
count := obj.edges[r]
@@ -124,7 +124,7 @@ func (obj *RefCount) EdgeInc(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (b
// reference for each arg name in the edge. Since this also decrements the
// references for the two input vertices, it returns the corresponding two
// boolean values for these calls. (This function makes two calls to VertexDec.)
func (obj *RefCount) EdgeDec(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (bool, bool) {
func (obj *Count) EdgeDec(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (bool, bool) {
for _, arg := range fe.Args { // ref count each arg
r := obj.makeEdge(f1, f2, arg)
count := obj.edges[r]
@@ -138,7 +138,7 @@ func (obj *RefCount) EdgeDec(f1, f2 interfaces.Func, fe *interfaces.FuncEdge) (b
}
// FreeVertex removes exactly one entry from the Vertices list or it errors.
func (obj *RefCount) FreeVertex(f interfaces.Func) error {
func (obj *Count) FreeVertex(f interfaces.Func) error {
if count, exists := obj.vertices[f]; !exists || count != 0 {
return fmt.Errorf("no vertex of count zero found")
}
@@ -147,8 +147,8 @@ func (obj *RefCount) FreeVertex(f interfaces.Func) error {
}
// FreeEdge removes exactly one entry from the Edges list or it errors.
func (obj *RefCount) FreeEdge(f1, f2 interfaces.Func, arg string) error {
found := []*RefCountEdge{}
func (obj *Count) FreeEdge(f1, f2 interfaces.Func, arg string) error {
found := []*CountEdge{}
for k, count := range obj.edges {
//if k == nil { // programming error
// continue
@@ -169,7 +169,7 @@ func (obj *RefCount) FreeEdge(f1, f2 interfaces.Func, arg string) error {
// GC runs the garbage collector on any zeroed references. Note the distinction
// between count == 0 (please delete now) and absent from the map.
func (obj *RefCount) GC(graphAPI interfaces.GraphAPI) error {
func (obj *Count) GC(graphAPI interfaces.GraphAPI) error {
// debug
//fmt.Printf("start refs\n%s", obj.String())
//defer func() { fmt.Printf("end refs\n%s", obj.String()) }()
@@ -265,7 +265,7 @@ func (obj *RefCount) GC(graphAPI interfaces.GraphAPI) error {
// makeEdge looks up an edge with the "hash" input we are seeking. If it doesn't
// find a match, it returns a new one with those fields.
func (obj *RefCount) makeEdge(f1, f2 interfaces.Func, arg string) *RefCountEdge {
func (obj *Count) makeEdge(f1, f2 interfaces.Func, arg string) *CountEdge {
for k := range obj.edges {
//if k == nil { // programming error
// continue
@@ -274,7 +274,7 @@ func (obj *RefCount) makeEdge(f1, f2 interfaces.Func, arg string) *RefCountEdge
return k
}
}
return &RefCountEdge{ // not found, so make a new one!
return &CountEdge{ // not found, so make a new one!
f1: f1,
f2: f2,
arg: arg,