github.com/rkt/rkt@v1.30.1-0.20200224141603-171c416fac02/store/imagestore/schema.go (about)

     1  // Copyright 2015 The rkt Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package imagestore
    16  
    17  import (
    18  	"database/sql"
    19  	"fmt"
    20  )
    21  
    22  const (
    23  	// Incremental db version at the current code revision.
    24  	dbVersion = 7
    25  )
    26  
    27  // Statement to run when creating a db. These are the statements to create the
    28  // db at the latest db version (dbVersion) provided by this rkt version.
    29  // If the db already exists migration statements should be executed
    30  var dbCreateStmts = [...]string{
    31  	// version table
    32  	"CREATE TABLE IF NOT EXISTS version (version int);",
    33  	fmt.Sprintf("INSERT INTO version VALUES (%d)", dbVersion),
    34  
    35  	// remote table. The primary key is "aciurl".
    36  	"CREATE TABLE IF NOT EXISTS remote (aciurl string, sigurl string, etag string, blobkey string, cachemaxage int, downloadtime time);",
    37  	"CREATE UNIQUE INDEX IF NOT EXISTS aciurlidx ON remote (aciurl)",
    38  
    39  	// aciinfo table. The primary key is "blobkey" and it matches the key used to save that aci in the blob store
    40  	"CREATE TABLE IF NOT EXISTS aciinfo (blobkey string, name string, importtime time, lastused time, latest bool, size int64 DEFAULT 0, treestoresize int64 DEFAULT 0);",
    41  	"CREATE UNIQUE INDEX IF NOT EXISTS blobkeyidx ON aciinfo (blobkey)",
    42  	"CREATE INDEX IF NOT EXISTS nameidx ON aciinfo (name)",
    43  }
    44  
    45  // dbIsPopulated checks if the db is already populated (at any version) verifing if the "version" table exists
    46  func dbIsPopulated(tx *sql.Tx) (bool, error) {
    47  	rows, err := tx.Query("SELECT Name FROM __Table where Name == $1", "version")
    48  	if err != nil {
    49  		return false, err
    50  	}
    51  	defer rows.Close()
    52  	count := 0
    53  	for rows.Next() {
    54  		count++
    55  	}
    56  	if err := rows.Err(); err != nil {
    57  		return false, err
    58  	}
    59  	if count > 0 {
    60  		return true, nil
    61  	}
    62  	return false, nil
    63  }
    64  
    65  // getDBVersion retrieves the current db version
    66  func getDBVersion(tx *sql.Tx) (int, error) {
    67  	var version int
    68  	rows, err := tx.Query("SELECT version FROM version")
    69  	if err != nil {
    70  		return -1, err
    71  	}
    72  	defer rows.Close()
    73  	found := false
    74  	for rows.Next() {
    75  		if err := rows.Scan(&version); err != nil {
    76  			return -1, err
    77  		}
    78  		found = true
    79  		break
    80  	}
    81  	if err := rows.Err(); err != nil {
    82  		return -1, err
    83  	}
    84  	if !found {
    85  		return -1, fmt.Errorf("db version table empty")
    86  	}
    87  	return version, nil
    88  }
    89  
    90  // updateDBVersion updates the db version
    91  func updateDBVersion(tx *sql.Tx, version int) error {
    92  	// ql doesn't have an INSERT OR UPDATE function so
    93  	// it's faster to remove and reinsert the row
    94  	_, err := tx.Exec("DELETE FROM version")
    95  	if err != nil {
    96  		return err
    97  	}
    98  	_, err = tx.Exec("INSERT INTO version VALUES ($1)", version)
    99  	if err != nil {
   100  		return err
   101  	}
   102  	return nil
   103  }