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* Always defer *sql.Rows.Close and consult with Err database/sql.Rows.Next() makes sure to call Close only after exhausting result rows which would NOT happen when returning early from a bad Scan. Close being idempotent makes it a great candidate to get always deferred regardless of what happens later on the result set. This change also makes sure call Err() after exhausting Next() and propagate non-nil results from it as the documentation advises. Closes #764 Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org> * Override named result parameters in last returns Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org> * Do the same over new changes that got merged Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org> Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
112 lines
3.7 KiB
Go
112 lines
3.7 KiB
Go
// Copyright 2017 Vector Creations Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package common
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import (
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"context"
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"database/sql"
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"strings"
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)
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const partitionOffsetsSchema = `
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-- The offsets that the server has processed up to.
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CREATE TABLE IF NOT EXISTS ${prefix}_partition_offsets (
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-- The name of the topic.
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topic TEXT NOT NULL,
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-- The 32-bit partition ID
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partition INTEGER NOT NULL,
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-- The 64-bit offset.
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partition_offset BIGINT NOT NULL,
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CONSTRAINT ${prefix}_topic_partition_unique UNIQUE (topic, partition)
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);
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`
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const selectPartitionOffsetsSQL = "" +
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"SELECT partition, partition_offset FROM ${prefix}_partition_offsets WHERE topic = $1"
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const upsertPartitionOffsetsSQL = "" +
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"INSERT INTO ${prefix}_partition_offsets (topic, partition, partition_offset) VALUES ($1, $2, $3)" +
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" ON CONFLICT ON CONSTRAINT ${prefix}_topic_partition_unique" +
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" DO UPDATE SET partition_offset = $3"
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// PartitionOffsetStatements represents a set of statements that can be run on a partition_offsets table.
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type PartitionOffsetStatements struct {
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selectPartitionOffsetsStmt *sql.Stmt
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upsertPartitionOffsetStmt *sql.Stmt
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}
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// Prepare converts the raw SQL statements into prepared statements.
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// Takes a prefix to prepend to the table name used to store the partition offsets.
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// This allows multiple components to share the same database schema.
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func (s *PartitionOffsetStatements) Prepare(db *sql.DB, prefix string) (err error) {
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_, err = db.Exec(strings.Replace(partitionOffsetsSchema, "${prefix}", prefix, -1))
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if err != nil {
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return
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}
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if s.selectPartitionOffsetsStmt, err = db.Prepare(
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strings.Replace(selectPartitionOffsetsSQL, "${prefix}", prefix, -1),
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); err != nil {
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return
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}
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if s.upsertPartitionOffsetStmt, err = db.Prepare(
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strings.Replace(upsertPartitionOffsetsSQL, "${prefix}", prefix, -1),
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); err != nil {
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return
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}
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return
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}
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// PartitionOffsets implements PartitionStorer
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func (s *PartitionOffsetStatements) PartitionOffsets(
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ctx context.Context, topic string,
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) ([]PartitionOffset, error) {
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return s.selectPartitionOffsets(ctx, topic)
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}
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// SetPartitionOffset implements PartitionStorer
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func (s *PartitionOffsetStatements) SetPartitionOffset(
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ctx context.Context, topic string, partition int32, offset int64,
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) error {
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return s.upsertPartitionOffset(ctx, topic, partition, offset)
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}
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// selectPartitionOffsets returns all the partition offsets for the given topic.
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func (s *PartitionOffsetStatements) selectPartitionOffsets(
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ctx context.Context, topic string,
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) ([]PartitionOffset, error) {
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rows, err := s.selectPartitionOffsetsStmt.QueryContext(ctx, topic)
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if err != nil {
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return nil, err
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}
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defer rows.Close() // nolint: errcheck
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var results []PartitionOffset
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for rows.Next() {
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var offset PartitionOffset
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if err := rows.Scan(&offset.Partition, &offset.Offset); err != nil {
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return nil, err
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}
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results = append(results, offset)
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}
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return results, rows.Err()
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}
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// UpsertPartitionOffset updates or inserts the partition offset for the given topic.
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func (s *PartitionOffsetStatements) upsertPartitionOffset(
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ctx context.Context, topic string, partition int32, offset int64,
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) error {
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_, err := s.upsertPartitionOffsetStmt.ExecContext(ctx, topic, partition, offset)
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return err
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}
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