feat(config file): add config file for frequently changing values

Author: Richard Baah

src/Backend/opti-sql-go/config/config.go

@@ -0,0 +1,185 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	kiloByte = 1024
+	megaByte = 1024 * kiloByte
+	gigaByte = 1024 * megaByte
+)
+
+type Config struct {
+	Server  serverConfig  `yaml:"server"`
+	Batch   batchConfig   `yaml:"batch"`
+	Query   queryConfig   `yaml:"query"`
+	Metrics metricsConfig `yaml:"metrics"`
+}
+type serverConfig struct {
+	Port             int    `yaml:"port"`
+	Host             string `yaml:"host"`
+	Timeout          int    `yaml:"timeout"`
+	MaxRequestSizeMB uint64 `yaml:"max_request_size_mb"` // max size of a file upload. passed in by grpc request
+}
+type batchConfig struct {
+	Size                  int    `yaml:"size"`
+	EnableParallelRead    bool   `yaml:"enable_parallel_read"`
+	MaxMemoryBeforeSplill uint64 `yaml:"max_memory_before_spill"`
+	MaxFileSizeMB         int    `yaml:"max_file_size_mb"` // max size of a single file
+}
+type queryConfig struct {
+	// should results be cached, server side? if so how long
+	EnableCache     bool `yaml:"enable_cache"`
+	CacheTTLSeconds int  `yaml:"cache_ttl_seconds"`
+	// run queries concurrently? if so what the max before blocking
+	EnableConcurrentExecution bool `yaml:"enable_concurrent_execution"`
+	MaxConcurrentQueries      int  `yaml:"max_concurrent_queries"` // blocks after this many concurrent queries until one finishes
+}
+type metricsConfig struct {
+	EnableMetrics      bool   `yaml:"enable_metrics"`
+	MetricsPort        int    `yaml:"metrics_port"`
+	MetricsHost        string `yaml:"metrics_host"`
+	ExportIntervalSecs int    `yaml:"export_interval_secs"`
+	// what queries have beeen sent
+	EnableQueryStats bool `yaml:"enable_query_stats"`
+	// memory usage over time
+	EnableMemoryStats bool `yaml:"enable_memory_stats"`
+}
+
+var configInstance *Config = &Config{
+	Server: serverConfig{
+		Port:             8080,
+		Host:             "localhost",
+		Timeout:          30,
+		MaxRequestSizeMB: 15,
+	},
+	Batch: batchConfig{
+		Size:                  1024 * 8, // rows per bathch
+		EnableParallelRead:    true,
+		MaxMemoryBeforeSplill: uint64(gigaByte) * 2, // 2GB
+		MaxFileSizeMB:         500,                  // 500MB
+	},
+	Query: queryConfig{
+		EnableCache:               true,
+		CacheTTLSeconds:           600, // 10 minutes
+		EnableConcurrentExecution: true,
+		MaxConcurrentQueries:      2, // 2 concurrent queries
+	},
+	Metrics: metricsConfig{
+		EnableMetrics:      true,
+		MetricsPort:        9999,
+		MetricsHost:        "localhost",
+		ExportIntervalSecs: 60, // 1 minute
+		EnableQueryStats:   true,
+		EnableMemoryStats:  true,
+	},
+}
+
+func GetConfig() *Config {
+	return configInstance
+}
+
+// overwrite global instance with loaded config
+func Decode(filePath string) error {
+	suffix := strings.Split(filePath, ".")[len(strings.Split(filePath, "."))-1]
+	if suffix != "yaml" && suffix != "yml" {
+		return errors.New("file must be a .yaml or .yml file")
+	}
+	r, err := os.Open(filePath)
+	if err != nil {
+		return err
+	}
+	config := make(map[string]interface{})
+	decoder := yaml.NewDecoder(r)
+	if err := decoder.Decode(config); err != nil {
+		return fmt.Errorf("failed to decode config: %w", err)
+	}
+	fmt.Printf("about to merge from -> %v\n", config)
+	mergeConfig(configInstance, config)
+	return nil
+}
+func mergeConfig(dst *Config, src map[string]interface{}) {
+	// =============================
+	// SERVER
+	// =============================
+	if server, ok := src["server"].(map[string]interface{}); ok {
+		if v, ok := server["port"].(int); ok {
+			dst.Server.Port = v
+		}
+		if v, ok := server["host"].(string); ok {
+			dst.Server.Host = v
+		}
+		if v, ok := server["timeout"].(int); ok {
+			dst.Server.Timeout = v
+		}
+		if v, ok := server["max_request_size_mb"].(int); ok {
+			dst.Server.MaxRequestSizeMB = uint64(v)
+		}
+	}
+
+	// =============================
+	// BATCH
+	// =============================
+	if batch, ok := src["batch"].(map[string]interface{}); ok {
+		if v, ok := batch["size"].(int); ok {
+			dst.Batch.Size = v
+		}
+		if v, ok := batch["enable_parallel_read"].(bool); ok {
+			dst.Batch.EnableParallelRead = v
+		}
+		if v, ok := batch["max_memory_before_spill"].(int); ok {
+			dst.Batch.MaxMemoryBeforeSplill = uint64(v)
+		}
+		if v, ok := batch["max_file_size_mb"].(int); ok {
+			dst.Batch.MaxFileSizeMB = v
+		}
+	}
+
+	// =============================
+	// QUERY
+	// =============================
+	if query, ok := src["query"].(map[string]interface{}); ok {
+		if v, ok := query["enable_cache"].(bool); ok {
+			dst.Query.EnableCache = v
+		}
+		if v, ok := query["cache_ttl_seconds"].(int); ok {
+			dst.Query.CacheTTLSeconds = v
+		}
+		if v, ok := query["enable_concurrent_execution"].(bool); ok {
+			dst.Query.EnableConcurrentExecution = v
+		}
+		if v, ok := query["max_concurrent_queries"].(int); ok {
+			dst.Query.MaxConcurrentQueries = v
+		}
+	}
+
+	// =============================
+	// METRICS
+	// =============================
+	if metrics, ok := src["metrics"].(map[string]interface{}); ok {
+		if v, ok := metrics["enable_metrics"].(bool); ok {
+			dst.Metrics.EnableMetrics = v
+		}
+		if v, ok := metrics["metrics_port"].(int); ok {
+			dst.Metrics.MetricsPort = v
+		}
+		if v, ok := metrics["metrics_host"].(string); ok {
+			dst.Metrics.MetricsHost = v
+		}
+		if v, ok := metrics["export_interval_secs"].(int); ok {
+			dst.Metrics.ExportIntervalSecs = v
+		}
+		if v, ok := metrics["enable_query_stats"].(bool); ok {
+			dst.Metrics.EnableQueryStats = v
+		}
+		if v, ok := metrics["enable_memory_stats"].(bool); ok {
+			dst.Metrics.EnableMemoryStats = v
+		}
+	}
+}