1 files changed, 113 insertions, 0 deletions
diff --git a/adapter/statsclient/stat_segment_api.go b/adapter/statsclient/stat_segment_api.go
new file mode 100644
index 0000000..f2e4219
--- /dev/null
+++ b/adapter/statsclient/stat_segment_api.go
@@ -0,0 +1,113 @@
+//  Copyright (c) 2020 Cisco and/or its affiliates.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at:
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+
+package statsclient
+
+import (
+	"fmt"
+	"git.fd.io/govpp.git/adapter"
+	"sync/atomic"
+	"time"
+	"unsafe"
+)
+
+var (
+	// ErrStatDataLenIncorrect is returned when stat data does not match vector
+	// length of a respective data directory
+	ErrStatDataLenIncorrect = fmt.Errorf("stat data length incorrect")
+)
+
+var (
+	MaxWaitInProgress    = time.Millisecond * 100
+	CheckDelayInProgress = time.Microsecond * 10
+)
+
+const (
+	minVersion = 1
+	maxVersion = 2
+)
+
+const (
+	statDirIllegal               = 0
+	statDirScalarIndex           = 1
+	statDirCounterVectorSimple   = 2
+	statDirCounterVectorCombined = 3
+	statDirErrorIndex            = 4
+	statDirNameVector            = 5
+	statDirEmpty                 = 6
+)
+
+type statDirectoryType int32
+
+type statDirectoryName []byte
+
+// statSegment represents common API for every stats API version
+type statSegment interface {
+	// GetDirectoryVector returns pointer to memory where the beginning
+	// of the data directory is located
+	GetDirectoryVector() (unsafe.Pointer, error)
+
+	// GetStatDirOnIndex accepts directory vector and particular index.
+	// Returns pointer to the beginning of the segment. Also the directory
+	// name as [128]byte and the directory type is returned for easy use
+	// without needing to know the exact segment version.
+	//
+	// Note that if the index is equal to 0, the result pointer points to
+	// the same memory address as the argument.
+	GetStatDirOnIndex(directory unsafe.Pointer, index uint32) (unsafe.Pointer, statDirectoryName, statDirectoryType)
+
+	// GetEpoch re-loads stats header and returns current epoch
+	//and 'inProgress' value
+	GetEpoch() (int64, bool)
+
+	// CopyEntryData accepts pointer to a directory segment and returns adapter.Stat
+	// based on directory type populated with data
+	CopyEntryData(segment unsafe.Pointer) adapter.Stat
+
+	// UpdateEntryData accepts pointer to a directory segment with data, and stat
+	// segment to update
+	UpdateEntryData(segment unsafe.Pointer, s *adapter.Stat) error
+}
+
+// vecHeader represents a vector header
+type vecHeader struct {
+	length     uint64
+	vectorData [0]uint8
+}
+
+func (t statDirectoryType) String() string {
+	return adapter.StatType(t).String()
+}
+
+func getVersion(data []byte) uint64 {
+	type apiVersion struct {
+		value uint64
+	}
+	header := (*apiVersion)(unsafe.Pointer(&data[0]))
+	version := &apiVersion{
+		value: atomic.LoadUint64(&header.value),
+	}
+	debugf("stats API version loaded: %d", version.value)
+	return version.value
+}
+
+func vectorLen(v unsafe.Pointer) unsafe.Pointer {
+	vec := *(*vecHeader)(unsafe.Pointer(uintptr(v) - unsafe.Sizeof(uint64(0))))
+	return unsafe.Pointer(&vec.length)
+}
+
+//go:nosplit
+func statSegPointer(p unsafe.Pointer, offset uintptr) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(p) + offset)
+}