1 files changed, 111 insertions, 0 deletions
diff --git a/internal/partition_offset_table.go b/internal/partition_offset_table.go
new file mode 100644
index 00000000..8b72819b
--- /dev/null
+++ b/internal/partition_offset_table.go
@@ -0,0 +1,111 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// 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 internal
+
+import (
+	"context"
+	"database/sql"
+	"strings"
+)
+
+const partitionOffsetsSchema = `
+-- The offsets that the server has processed up to.
+CREATE TABLE IF NOT EXISTS ${prefix}_partition_offsets (
+    -- The name of the topic.
+    topic TEXT NOT NULL,
+    -- The 32-bit partition ID
+    partition INTEGER NOT NULL,
+    -- The 64-bit offset.
+    partition_offset BIGINT NOT NULL,
+    UNIQUE (topic, partition)
+);
+`
+
+const selectPartitionOffsetsSQL = "" +
+	"SELECT partition, partition_offset FROM ${prefix}_partition_offsets WHERE topic = $1"
+
+const upsertPartitionOffsetsSQL = "" +
+	"INSERT INTO ${prefix}_partition_offsets (topic, partition, partition_offset) VALUES ($1, $2, $3)" +
+	" ON CONFLICT (topic, partition)" +
+	" DO UPDATE SET partition_offset = $3"
+
+// PartitionOffsetStatements represents a set of statements that can be run on a partition_offsets table.
+type PartitionOffsetStatements struct {
+	selectPartitionOffsetsStmt *sql.Stmt
+	upsertPartitionOffsetStmt  *sql.Stmt
+}
+
+// Prepare converts the raw SQL statements into prepared statements.
+// Takes a prefix to prepend to the table name used to store the partition offsets.
+// This allows multiple components to share the same database schema.
+func (s *PartitionOffsetStatements) Prepare(db *sql.DB, prefix string) (err error) {
+	_, err = db.Exec(strings.Replace(partitionOffsetsSchema, "${prefix}", prefix, -1))
+	if err != nil {
+		return
+	}
+	if s.selectPartitionOffsetsStmt, err = db.Prepare(
+		strings.Replace(selectPartitionOffsetsSQL, "${prefix}", prefix, -1),
+	); err != nil {
+		return
+	}
+	if s.upsertPartitionOffsetStmt, err = db.Prepare(
+		strings.Replace(upsertPartitionOffsetsSQL, "${prefix}", prefix, -1),
+	); err != nil {
+		return
+	}
+	return
+}
+
+// PartitionOffsets implements PartitionStorer
+func (s *PartitionOffsetStatements) PartitionOffsets(
+	ctx context.Context, topic string,
+) ([]PartitionOffset, error) {
+	return s.selectPartitionOffsets(ctx, topic)
+}
+
+// SetPartitionOffset implements PartitionStorer
+func (s *PartitionOffsetStatements) SetPartitionOffset(
+	ctx context.Context, topic string, partition int32, offset int64,
+) error {
+	return s.upsertPartitionOffset(ctx, topic, partition, offset)
+}
+
+// selectPartitionOffsets returns all the partition offsets for the given topic.
+func (s *PartitionOffsetStatements) selectPartitionOffsets(
+	ctx context.Context, topic string,
+) ([]PartitionOffset, error) {
+	rows, err := s.selectPartitionOffsetsStmt.QueryContext(ctx, topic)
+	if err != nil {
+		return nil, err
+	}
+	defer CloseAndLogIfError(ctx, rows, "selectPartitionOffsets: rows.close() failed")
+	var results []PartitionOffset
+	for rows.Next() {
+		var offset PartitionOffset
+		if err := rows.Scan(&offset.Partition, &offset.Offset); err != nil {
+			return nil, err
+		}
+		results = append(results, offset)
+	}
+	return results, rows.Err()
+}
+
+// UpsertPartitionOffset updates or inserts the partition offset for the given topic.
+func (s *PartitionOffsetStatements) upsertPartitionOffset(
+	ctx context.Context, topic string, partition int32, offset int64,
+) error {
+	_, err := s.upsertPartitionOffsetStmt.ExecContext(ctx, topic, partition, offset)
+	return err
+}