runtime: add tests for addrRanges.add

Change-Id: I249deb482df74068b0538e9d773b9a87bc5a6df3
Reviewed-on: https://go-review.googlesource.com/c/go/+/242681
Run-TryBot: Michael Knyszek <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Michael Knyszek <[email protected]>
Reviewed-by: Austin Clements <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>

Author: mknyszek

src/runtime/export_test.go

@@ -785,22 +785,64 @@ func (a AddrRange) Equals(b AddrRange) bool {
 	return a == b
 }
 
+// Size returns the size in bytes of the address range.
+func (a AddrRange) Size() uintptr {
+	return a.addrRange.size()
+}
+
 // AddrRanges is a wrapper around addrRanges for testing.
 type AddrRanges struct {
 	addrRanges
+	mutable bool
+}
+
+// NewAddrRanges creates a new empty addrRanges.
+//
+// Note that this initializes addrRanges just like in the
+// runtime, so its memory is persistentalloc'd. Call this
+// function sparingly since the memory it allocates is
+// leaked.
+//
+// This AddrRanges is mutable, so we can test methods like
+// Add.
+func NewAddrRanges() AddrRanges {
+	r := addrRanges{}
+	r.init(new(uint64))
+	return AddrRanges{r, true}
 }
 
 // MakeAddrRanges creates a new addrRanges populated with
 // the ranges in a.
+//
+// The returned AddrRanges is immutable, so methods like
+// Add will fail.
 func MakeAddrRanges(a ...AddrRange) AddrRanges {
 	// Methods that manipulate the backing store of addrRanges.ranges should
 	// not be used on the result from this function (e.g. add) since they may
-	// trigger reallocation.
+	// trigger reallocation. That would normally be fine, except the new
+	// backing store won't come from the heap, but from persistentalloc, so
+	// we'll leak some memory implicitly.
 	ranges := make([]addrRange, 0, len(a))
+	total := uintptr(0)
 	for _, r := range a {
 		ranges = append(ranges, r.addrRange)
+		total += r.Size()
+	}
+	return AddrRanges{addrRanges{
+		ranges:     ranges,
+		totalBytes: total,
+		sysStat:    new(uint64),
+	}, false}
+}
+
+// Ranges returns a copy of the ranges described by the
+// addrRanges.
+func (a *AddrRanges) Ranges() []AddrRange {
+	result := make([]AddrRange, 0, len(a.addrRanges.ranges))
+	for _, r := range a.addrRanges.ranges {
+		result = append(result, AddrRange{r})
 	}
-	return AddrRanges{addrRanges{ranges: ranges, sysStat: new(uint64)}}
+	return result
 }
 
 // FindSucc returns the successor to base. See addrRanges.findSucc
@@ -809,6 +851,22 @@ func (a *AddrRanges) FindSucc(base uintptr) int {
 	return a.findSucc(base)
 }
 
+// Add adds a new AddrRange to the AddrRanges.
+//
+// The AddrRange must be mutable (i.e. created by NewAddrRanges),
+// otherwise this method will throw.
+func (a *AddrRanges) Add(r AddrRange) {
+	if !a.mutable {
+		throw("attempt to mutate immutable AddrRanges")
+	}
+	a.add(r.addrRange)
+}
+
+// TotalBytes returns the totalBytes field of the addrRanges.
+func (a *AddrRanges) TotalBytes() uintptr {
+	return a.addrRanges.totalBytes
+}
+
 // BitRange represents a range over a bitmap.
 type BitRange struct {
 	I, N uint // bit index and length in bits

src/runtime/mranges_test.go

@@ -9,6 +9,109 @@ import (
 	"testing"
 )
 
+func validateAddrRanges(t *testing.T, a *AddrRanges, want ...AddrRange) {
+	ranges := a.Ranges()
+	if len(ranges) != len(want) {
+		t.Errorf("want %v, got %v", want, ranges)
+		t.Fatal("different lengths")
+	}
+	gotTotalBytes := uintptr(0)
+	wantTotalBytes := uintptr(0)
+	for i := range ranges {
+		gotTotalBytes += ranges[i].Size()
+		wantTotalBytes += want[i].Size()
+		if ranges[i].Base() >= ranges[i].Limit() {
+			t.Error("empty range found")
+		}
+		// Ensure this is equivalent to what we want.
+		if !ranges[i].Equals(want[i]) {
+			t.Errorf("range %d: got [0x%x, 0x%x), want [0x%x, 0x%x)", i,
+				ranges[i].Base(), ranges[i].Limit(),
+				want[i].Base(), want[i].Limit(),
+			)
+		}
+		if i != 0 {
+			// Ensure the ranges are sorted.
+			if ranges[i-1].Base() >= ranges[i].Base() {
+				t.Errorf("ranges %d and %d are out of sorted order", i-1, i)
+			}
+			// Check for a failure to coalesce.
+			if ranges[i-1].Limit() == ranges[i].Base() {
+				t.Errorf("ranges %d and %d should have coalesced", i-1, i)
+			}
+			// Check if any ranges overlap. Because the ranges are sorted
+			// by base, it's sufficient to just check neighbors.
+			if ranges[i-1].Limit() > ranges[i].Base() {
+				t.Errorf("ranges %d and %d overlap", i-1, i)
+			}
+		}
+	}
+	if wantTotalBytes != gotTotalBytes {
+		t.Errorf("expected %d total bytes, got %d", wantTotalBytes, gotTotalBytes)
+	}
+	if b := a.TotalBytes(); b != gotTotalBytes {
+		t.Errorf("inconsistent total bytes: want %d, got %d", gotTotalBytes, b)
+	}
+	if t.Failed() {
+		t.Errorf("addrRanges: %v", ranges)
+		t.Fatal("detected bad addrRanges")
+	}
+}
+
+func TestAddrRangesAdd(t *testing.T) {
+	a := NewAddrRanges()
+
+	// First range.
+	a.Add(MakeAddrRange(512, 1024))
+	validateAddrRanges(t, &a,
+		MakeAddrRange(512, 1024),
+	)
+
+	// Coalesce up.
+	a.Add(MakeAddrRange(1024, 2048))
+	validateAddrRanges(t, &a,
+		MakeAddrRange(512, 2048),
+	)
+
+	// Add new independent range.
+	a.Add(MakeAddrRange(4096, 8192))
+	validateAddrRanges(t, &a,
+		MakeAddrRange(512, 2048),
+		MakeAddrRange(4096, 8192),
+	)
+
+	// Coalesce down.
+	a.Add(MakeAddrRange(3776, 4096))
+	validateAddrRanges(t, &a,
+		MakeAddrRange(512, 2048),
+		MakeAddrRange(3776, 8192),
+	)
+
+	// Coalesce up and down.
+	a.Add(MakeAddrRange(2048, 3776))
+	validateAddrRanges(t, &a,
+		MakeAddrRange(512, 8192),
+	)
+
+	// Push a bunch of independent ranges to the end to try and force growth.
+	expectedRanges := []AddrRange{MakeAddrRange(512, 8192)}
+	for i := uintptr(0); i < 64; i++ {
+		dRange := MakeAddrRange(8192+(i+1)*2048, 8192+(i+1)*2048+10)
+		a.Add(dRange)
+		expectedRanges = append(expectedRanges, dRange)
+		validateAddrRanges(t, &a, expectedRanges...)
+	}
+
+	// Push a bunch of independent ranges to the beginning to try and force growth.
+	var bottomRanges []AddrRange
+	for i := uintptr(0); i < 63; i++ {
+		dRange := MakeAddrRange(8+i*8, 8+i*8+4)
+		a.Add(dRange)
+		bottomRanges = append(bottomRanges, dRange)
+		validateAddrRanges(t, &a, append(bottomRanges, expectedRanges...)...)
+	}
+}
+
 func TestAddrRangesFindSucc(t *testing.T) {
 	var large []AddrRange
 	for i := 0; i < 100; i++ {