Add Compose method (#71)

.github/workflows/test-v1.yml

@@ -5,12 +5,14 @@ on:
     paths-ignore:
       - README.md
       - .github/workflows/test-v2.yml
-      - 'v2/**'
+      - v2/**
   pull_request:
     paths-ignore:
       - README.md
       - .github/workflows/test-v2.yml
-      - 'v2/**'
+      - v2/**
+
+permissions: read-all
 
 jobs:
   test-v1:
@@ -30,7 +32,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Set up Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v5
         with:
           go-version: ${{matrix.go-version}}
 

.github/workflows/test-v2.yml

@@ -5,12 +5,14 @@ on:
     paths:
       - README.md
       - .github/workflows/test-v2.yml
-      - 'v2/**'
+      - v2/**
   pull_request:
     paths:
       - README.md
       - .github/workflows/test-v2.yml
-      - 'v2/**'
+      - v2/**
+
+permissions: read-all
 
 jobs:
   test-v2:

.gitignore

@@ -1,2 +1,4 @@
+example/example
 example/sonyflake_server
+v2/example/example
 v2/example/sonyflake_server

example/Dockerfile

@@ -1,6 +1,9 @@
 FROM ubuntu:14.04
 
-ADD ./sonyflake_server /
-ENTRYPOINT ["/sonyflake_server"]
+COPY ./sonyflake_server /sonyflake_server
 
+RUN useradd -m sonyflake
+USER sonyflake
+
+ENTRYPOINT ["/sonyflake_server"]
 EXPOSE 8080

example/README.md

@@ -1,21 +1,19 @@
-Example
-=======
+# Example
 
 This example runs Sonyflake on AWS Elastic Beanstalk.
 
-Setup
------
+## Setup
 
 1. Build the cross compiler for linux/amd64 if using other platforms.
 
-  ```
-  cd $GOROOT/src && GOOS=linux GOARCH=amd64 ./make.bash
-  ```
+   ```bash
+   cd $GOROOT/src && GOOS=linux GOARCH=amd64 ./make.bash
+   ```
 
 2. Build sonyflake_server in the example directory.
 
-  ```
-  ./linux64_build.sh
-  ```
+   ```bash
+   ./linux64_build.sh
+   ```
 
 3. Upload the example directory to AWS Elastic Beanstalk.

v2/example/Dockerfile

@@ -1,6 +1,9 @@
 FROM ubuntu:24.04
 
-ADD ./sonyflake_server /
-ENTRYPOINT ["/sonyflake_server"]
+COPY ./sonyflake_server /sonyflake_server
 
+RUN useradd -m sonyflake
+USER sonyflake
+
+ENTRYPOINT ["/sonyflake_server"]
 EXPOSE 8080

v2/example/README.md

@@ -1,21 +1,19 @@
-Example
-=======
+# Example
 
 This example runs Sonyflake on AWS Elastic Beanstalk.
 
-Setup
------
+## Setup
 
 1. Build the cross compiler for linux/amd64 if using other platforms.
 
-  ```
-  cd $GOROOT/src && GOOS=linux GOARCH=amd64 ./make.bash
-  ```
+   ```bash
+   cd $GOROOT/src && GOOS=linux GOARCH=amd64 ./make.bash
+   ```
 
 2. Build sonyflake_server in the example directory.
 
-  ```
-  ./linux64_build.sh
-  ```
+   ```bash
+   ./linux64_build.sh
+   ```
 
 3. Upload the example directory to AWS Elastic Beanstalk.

v2/sonyflake.go

@@ -247,10 +247,22 @@ func lower16BitPrivateIP(interfaceAddrs types.InterfaceAddrs) (int, error) {
 	return int(ip[2])<<8 + int(ip[3]), nil
 }
 
+// ToTime returns the time when the given ID was generated.
 func (sf *Sonyflake) ToTime(id int64) time.Time {
 	return time.Unix(0, (sf.startTime+sf.timePart(id))*sf.timeUnit)
 }
 
+// Compose creates a Sonyflake ID from its components.
+// The time parameter should be the time when the ID was generated.
+// The sequence parameter should be between 0 and 2^BitsSequence-1 (inclusive).
+// The machineID parameter should be between 0 and 2^BitsMachineID-1 (inclusive).
+func (sf *Sonyflake) Compose(t time.Time, sequence, machineID int) int64 {
+	elapsedTime := sf.toInternalTime(t.UTC()) - sf.startTime
+	return elapsedTime<<(sf.bitsSequence+sf.bitsMachine) |
+		int64(sequence)<<sf.bitsMachine |
+		int64(machineID)
+}
+
 // Decompose returns a set of Sonyflake ID parts.
 func (sf *Sonyflake) Decompose(id int64) map[string]int64 {
 	time := sf.timePart(id)

v2/sonyflake_test.go

@@ -253,22 +253,6 @@ func TestNextID_ReturnsError(t *testing.T) {
 	}
 }
 
-func TestToTime(t *testing.T) {
-	start := time.Now()
-	sf := newSonyflake(t, Settings{
-		TimeUnit:  time.Millisecond,
-		StartTime: start,
-	})
-
-	id := nextID(t, sf)
-
-	tm := sf.ToTime(id)
-	diff := tm.Sub(start)
-	if diff < 0 || diff >= time.Duration(sf.timeUnit) {
-		t.Errorf("unexpected time: %v", tm)
-	}
-}
-
 func TestPrivateIPv4(t *testing.T) {
 	testCases := []struct {
 		description    string
@@ -351,3 +335,87 @@ func TestLower16BitPrivateIP(t *testing.T) {
 		})
 	}
 }
+
+func TestToTime(t *testing.T) {
+	start := time.Now()
+	sf := newSonyflake(t, Settings{
+		TimeUnit:  time.Millisecond,
+		StartTime: start,
+	})
+
+	id := nextID(t, sf)
+
+	tm := sf.ToTime(id)
+	diff := tm.Sub(start)
+	if diff < 0 || diff >= time.Duration(sf.timeUnit) {
+		t.Errorf("unexpected time: %v", tm)
+	}
+}
+
+func TestComposeAndDecompose(t *testing.T) {
+	now := time.Now()
+	sf := newSonyflake(t, Settings{
+		TimeUnit:  time.Millisecond,
+		StartTime: now,
+	})
+
+	testCases := []struct {
+		name      string
+		time      time.Time
+		sequence  int
+		machineID int
+	}{
+		{
+			name:      "zero values",
+			time:      now,
+			sequence:  0,
+			machineID: 0,
+		},
+		{
+			name:      "max sequence",
+			time:      now,
+			sequence:  1<<sf.bitsSequence - 1,
+			machineID: 0,
+		},
+		{
+			name:      "max machine id",
+			time:      now,
+			sequence:  0,
+			machineID: 1<<sf.bitsMachine - 1,
+		},
+		{
+			name:      "future time",
+			time:      now.Add(time.Hour),
+			sequence:  0,
+			machineID: 0,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			id := sf.Compose(tc.time, tc.sequence, tc.machineID)
+			parts := sf.Decompose(id)
+
+			// Verify time part
+			expectedTime := sf.toInternalTime(tc.time.UTC()) - sf.startTime
+			if parts["time"] != expectedTime {
+				t.Errorf("time mismatch: got %d, want %d", parts["time"], expectedTime)
+			}
+
+			// Verify sequence part
+			if parts["sequence"] != int64(tc.sequence) {
+				t.Errorf("sequence mismatch: got %d, want %d", parts["sequence"], tc.sequence)
+			}
+
+			// Verify machine id part
+			if parts["machine"] != int64(tc.machineID) {
+				t.Errorf("machine id mismatch: got %d, want %d", parts["machine"], tc.machineID)
+			}
+
+			// Verify id part
+			if parts["id"] != id {
+				t.Errorf("id mismatch: got %d, want %d", parts["id"], id)
+			}
+		})
+	}
+}