Permify / permify

package postgres

import (

	"context"

	"fmt"

	"strings"

	"time"

	"github.com/cenkalti/backoff/v4"

	"golang.org/x/exp/slog"

	"github.com/jackc/pgx/v5"

	"github.com/jackc/pgx/v5/pgxpool"

	"github.com/Masterminds/squirrel"

)

// Postgres - Structure for Postresql instance

type Postgres struct {

	ReadPool  *pgxpool.Pool

	WritePool *pgxpool.Pool

	Builder squirrel.StatementBuilderType

	// options

	maxDataPerWrite       int

	maxRetries            int

	watchBufferSize       int

	maxConnectionLifeTime time.Duration

	maxConnectionIdleTime time.Duration

	maxOpenConnections    int

	maxIdleConnections    int

}

// New - Creates new postgresql db instance

func New(uri string, opts ...Option) (*Postgres, error) {

	pg := &Postgres{

		maxOpenConnections: _defaultMaxOpenConnections,

		maxIdleConnections: _defaultMaxIdleConnections,

		maxDataPerWrite:    _defaultMaxDataPerWrite,

		maxRetries:         _defaultMaxRetries,

		watchBufferSize:    _defaultWatchBufferSize,

	}

	// Custom options

	for _, opt := range opts {

		opt(pg)

	}

	pg.Builder = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

	writeConfig, err := pgxpool.ParseConfig(uri)

	if err != nil {

		return nil, err

	}

	readConfig, err := pgxpool.ParseConfig(uri)

	if err != nil {

		return nil, err

	}

	// Set the default execution mode for queries using the write and read configurations.

	setDefaultQueryExecMode(writeConfig.ConnConfig)

	setDefaultQueryExecMode(readConfig.ConnConfig)

	// Set the plan cache mode for both write and read configurations to optimize query planning.

	setPlanCacheMode(writeConfig.ConnConfig)

	setPlanCacheMode(readConfig.ConnConfig)

	// Set the minimum number of idle connections in the pool for both write and read configurations.

	writeConfig.MinConns = int32(pg.maxIdleConnections)

	readConfig.MinConns = int32(pg.maxIdleConnections)

	// Set the maximum number of active connections in the pool for both write and read configurations.

	writeConfig.MaxConns = int32(pg.maxOpenConnections)

	readConfig.MaxConns = int32(pg.maxOpenConnections)

	// Set the maximum amount of time a connection may be idle before being closed for both configurations.

	writeConfig.MaxConnIdleTime = pg.maxConnectionIdleTime

	readConfig.MaxConnIdleTime = pg.maxConnectionIdleTime

	// Set the maximum lifetime of a connection in the pool for both configurations.

	writeConfig.MaxConnLifetime = pg.maxConnectionLifeTime

	readConfig.MaxConnLifetime = pg.maxConnectionLifeTime

	// Set a jitter to the maximum connection lifetime to prevent all connections from expiring at the same time.

	writeConfig.MaxConnLifetimeJitter = time.Duration(0.2 * float64(pg.maxConnectionLifeTime))

	readConfig.MaxConnLifetimeJitter = time.Duration(0.2 * float64(pg.maxConnectionLifeTime))

	// Create connection pools for both writing and reading operations using the configured settings.

	pg.WritePool, pg.ReadPool, err = createPools(

		context.Background(), // Context used to control the lifecycle of the pools.

		writeConfig,          // Configuration settings for the write pool.

		readConfig,           // Configuration settings for the read pool.

	)

	// Handle errors during the creation of the connection pools.

	if err != nil {

		return nil, err

	}

	return pg, nil

}

func (p *Postgres) GetMaxDataPerWrite() int {

	return p.maxDataPerWrite

}

func (p *Postgres) GetMaxRetries() int {

	return p.maxRetries

}

func (p *Postgres) GetWatchBufferSize() int {

	return p.watchBufferSize

}

// GetEngineType - Get the engine type which is postgresql in string

func (p *Postgres) GetEngineType() string {

	return "postgres"

}

// Close - Close postgresql instance

func (p *Postgres) Close() error {

	p.ReadPool.Close()

	p.WritePool.Close()

	return nil

}

// IsReady - Check if database is ready

func (p *Postgres) IsReady(ctx context.Context) (bool, error) {

	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)

	defer cancel()

	if err := p.ReadPool.Ping(ctx); err != nil {

		return false, err

	}

	return true, nil

}

var queryExecModes = map[string]pgx.QueryExecMode{

	"cache_statement": pgx.QueryExecModeCacheStatement,

	"cache_describe":  pgx.QueryExecModeCacheDescribe,

	"describe_exec":   pgx.QueryExecModeDescribeExec,

	"mode_exec":       pgx.QueryExecModeExec,

	"simple_protocol": pgx.QueryExecModeSimpleProtocol,

}

func setDefaultQueryExecMode(config *pgx.ConnConfig) {

	// Default mode if no specific mode is found in the connection string

	defaultMode := "cache_statement"

	// Iterate through the map keys to check if any are mentioned in the connection string

	for key := range queryExecModes {

		if strings.Contains(config.ConnString(), "default_query_exec_mode="+key) {

			config.DefaultQueryExecMode = queryExecModes[key]

			slog.Info("setDefaultQueryExecMode", slog.String("mode", key))

			return

		}

	}

	// Set to default mode if no matching mode is found

	config.DefaultQueryExecMode = queryExecModes[defaultMode]

	slog.Warn("setDefaultQueryExecMode", slog.String("mode", defaultMode))

}

var planCacheModes = map[string]string{

	"auto":              "auto",

	"force_custom_plan": "force_custom_plan",

}

func setPlanCacheMode(config *pgx.ConnConfig) {

	// Default mode if no specific mode is found in the connection string

	defaultMode := "auto"

	// Check if a plan cache mode is mentioned in the connection string and set it

	for key := range planCacheModes {

		if strings.Contains(config.ConnString(), "plan_cache_mode="+key) {

			config.Config.RuntimeParams["plan_cache_mode"] = planCacheModes[key]

			slog.Info("setPlanCacheMode", slog.String("mode", key))

			return

		}

	}

	// Set to default mode if no matching mode is found

	config.Config.RuntimeParams["plan_cache_mode"] = planCacheModes[defaultMode]

	slog.Warn("setPlanCacheMode", slog.String("mode", defaultMode))

}

// createPools initializes read and write connection pools with appropriate configurations and error handling.

func createPools(ctx context.Context, wConfig, rConfig *pgxpool.Config) (*pgxpool.Pool, *pgxpool.Pool, error) {

	// Context with timeout for creating the pools

	initCtx, cancel := context.WithTimeout(ctx, 10*time.Second)

	defer cancel()

	// Create write pool

	writePool, err := pgxpool.NewWithConfig(initCtx, wConfig)

	if err != nil {

	}

	// Create read pool using the same configuration

	readPool, err := pgxpool.NewWithConfig(initCtx, rConfig)

	if err != nil {

		writePool.Close() // Ensure write pool is closed on failure

	}

	// Set up retry policy for pinging pools

	retryPolicy := backoff.NewExponentialBackOff()

	retryPolicy.MaxElapsedTime = 1 * time.Minute

	// Attempt to ping both pools to confirm connectivity

	err = backoff.Retry(func() error {

		pingCtx, pingCancel := context.WithTimeout(context.Background(), 2*time.Second)

		defer pingCancel()

		if err := writePool.Ping(pingCtx); err != nil {

		}

		if err := readPool.Ping(pingCtx); err != nil {

		}

		return nil

	}, retryPolicy)

	// Handle errors from pinging

	if err != nil {

		writePool.Close()

		readPool.Close()

	}

	return writePool, readPool, nil

}