feat: simplify+improve resolver implementation / glob search

Signed-off-by: Keith Zantow <keith.zantow@anchore.com>

internal/archive/limits.go

@@ -59,21 +59,21 @@ func (l *Limiter) InUse() (memory, disk int64) {
 	return l.memory, l.disk
 }
 
-// Charge starts accounting for one archive. Releasing the charge gives back everything it took.
-func (l *Limiter) Charge() *Charge {
+// charge starts accounting for one archive. Releasing the charge gives back everything it took.
+func (l *Limiter) charge() *charge {
 	if l == nil {
 		return nil
 	}
-	return &Charge{limiter: l}
+	return &charge{limiter: l}
 }
 
-// Charge is one archive's draw on a Limiter. A nil *Charge admits everything.
+// charge is one archive's draw on a Limiter. A nil *charge admits everything.
 //
 // Bytes are charged as they land, never from the sizes an archive declares, since those can lie.
-type Charge struct {
-	limiter *Limiter
-	memory  int64
-	disk    int64
+type charge struct {
+	limiter  *Limiter
+	inMemory int64
+	onDisk   int64
 }
 
 func admits(limit, held, n int64) bool {
@@ -87,9 +87,9 @@ func admits(limit, held, n int64) bool {
 	}
 }
 
-// Memory charges n bytes held in memory, or reports false (charging nothing) when the memory limit
+// memory charges n bytes held in memory, or reports false (charging nothing) when the memory limit
 // does not admit them.
-func (c *Charge) Memory(n int64) bool {
+func (c *charge) memory(n int64) bool {
 	if c == nil || n <= 0 {
 		return true
 	}
@@ -100,14 +100,14 @@ func (c *Charge) Memory(n int64) bool {
 		return false
 	}
 	l.memory += n
-	c.memory += n
+	c.inMemory += n
 	l.peakMemory = max(l.peakMemory, l.memory)
 	return true
 }
 
-// Disk charges n bytes written to disk, or reports false (charging nothing) when the disk limit does
+// disk charges n bytes written to disk, or reports false (charging nothing) when the disk limit does
 // not admit them.
-func (c *Charge) Disk(n int64) bool {
+func (c *charge) disk(n int64) bool {
 	if c == nil || n <= 0 {
 		return true
 	}
@@ -118,53 +118,56 @@ func (c *Charge) Disk(n int64) bool {
 		return false
 	}
 	l.disk += n
-	c.disk += n
+	c.onDisk += n
 	l.peakDisk = max(l.peakDisk, l.disk)
 	return true
 }
 
-// Index charges n bytes of index bookkeeping. The index always lives in memory, but a zero memory
-// limit is a valid configuration that must still index archives, so it falls back to the disk
-// budget when memory does not admit it. Reports false only when neither does.
-func (c *Charge) Index(n int64) bool {
-	return c.Memory(n) || c.Disk(n)
+// index charges n bytes of index bookkeeping, which lives in memory whatever the limits say. A zero
+// memory limit is a valid configuration that must still index archives, so only then does the cost
+// fall back to the disk budget; a bounded memory limit bounds the index too.
+func (c *charge) index(n int64) bool {
+	if c.memory(n) {
+		return true
+	}
+	return c != nil && c.limiter.limits.MaxMemoryBytes == 0 && c.disk(n)
 }
 
-// RefundMemory gives back n bytes no longer held in memory.
-func (c *Charge) RefundMemory(n int64) {
+// refundMemory gives back n bytes no longer held in memory.
+func (c *charge) refundMemory(n int64) {
 	if c == nil || n <= 0 {
 		return
 	}
 	l := c.limiter
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	n = min(n, c.memory)
+	n = min(n, c.inMemory)
 	l.memory -= n
-	c.memory -= n
+	c.inMemory -= n
 }
 
-// RefundDisk gives back n bytes no longer on disk.
-func (c *Charge) RefundDisk(n int64) {
+// refundDisk gives back n bytes no longer on disk.
+func (c *charge) refundDisk(n int64) {
 	if c == nil || n <= 0 {
 		return
 	}
 	l := c.limiter
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	n = min(n, c.disk)
+	n = min(n, c.onDisk)
 	l.disk -= n
-	c.disk -= n
+	c.onDisk -= n
 }
 
-// Release gives back everything this charge took. Safe to call more than once.
-func (c *Charge) Release() {
+// release gives back everything this charge took. Safe to call more than once.
+func (c *charge) release() {
 	if c == nil {
 		return
 	}
 	l := c.limiter
 	l.mu.Lock()
 	defer l.mu.Unlock()
-	l.memory -= c.memory
-	l.disk -= c.disk
-	c.memory, c.disk = 0, 0
+	l.memory -= c.inMemory
+	l.disk -= c.onDisk
+	c.inMemory, c.onDisk = 0, 0
 }