Health and Administration

The GQLDB Java driver provides methods for monitoring server health, managing caches, and gathering statistics.

Health Service Methods

Admin Service Methods

Health Checks

healthCheck()

Check the current health status of the server:

Java
import com.gqldb.*;
import com.gqldb.types.HealthStatus;

public void checkHealth(GqldbClient client) {
    // Check overall server health
    HealthStatus status = client.healthCheck();

    switch (status) {
        case SERVING:
            System.out.println("Server is healthy and serving requests");
            break;
        case NOT_SERVING:
            System.out.println("Server is not serving requests");
            break;
        case SERVICE_UNKNOWN:
            System.out.println("Service status is unknown");
            break;
        case UNKNOWN:
            System.out.println("Health status is unknown");
            break;
    }

    // Check specific service health
    HealthStatus queryServiceStatus = client.healthCheck("query");
    System.out.println("Query service: " + queryServiceStatus);
}

HealthStatus Enum

Java
public enum HealthStatus {
    UNKNOWN,
    SERVING,
    NOT_SERVING,
    SERVICE_UNKNOWN
}

watch()

Monitor health status changes with server-side streaming:

Java
import com.gqldb.*;
import com.gqldb.types.HealthStatus;

public void watchHealth(GqldbClient client) {
    GqldbClient.HealthWatcher watcher = client.watch(status -> {
        System.out.println("Health status changed: " + status);

        if (status != HealthStatus.SERVING) {
            System.out.println("WARNING: Server is not healthy!");
            // Trigger alerts, failover logic, etc.
        }
    });

    // Let it run for some time
    try {
        Thread.sleep(300000);  // 5 minutes
    } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
    }

    // Stop watching
    watcher.stop();
    System.out.println("Stopped health monitoring");

    // Check for errors
    if (watcher.hasError()) {
        System.err.println("Watch error: " + watcher.getError().getMessage());
    }
}

HealthWatcher Class

Java
public static class HealthWatcher {
    void stop();                    // Stop watching
    boolean isCompleted();          // Check if watch has completed
    Throwable getError();           // Get any error that occurred
    boolean hasError();             // Check if an error occurred
}

Cache Management

CacheType Enum

Java
public enum CacheType {
    ALL,    // All caches
    AST,    // Abstract Syntax Tree cache
    PLAN    // Query plan cache
}

getCacheStats()

Get statistics about caches:

Java
import com.gqldb.*;
import com.gqldb.types.CacheType;
import com.gqldb.services.AdminService;

public void getCacheStatistics(GqldbClient client) {
    // Get all cache stats
    AdminService.CacheStats allStats = client.getCacheStats(CacheType.ALL);
    System.out.println("All cache stats: " + allStats);

    // Get AST cache stats
    AdminService.CacheStats astStats = client.getCacheStats(CacheType.AST);
    System.out.println("AST cache: " + astStats);

    // Get plan cache stats
    AdminService.CacheStats planStats = client.getCacheStats(CacheType.PLAN);
    System.out.println("Plan cache: " + planStats);
}

clearCache()

Clear caches to free memory or force recompilation:

Java
public void clearCaches(GqldbClient client) {
    // Clear all caches
    client.clearCache(CacheType.ALL);
    System.out.println("All caches cleared");

    // Clear only AST cache
    client.clearCache(CacheType.AST);
    System.out.println("AST cache cleared");

    // Clear only plan cache
    client.clearCache(CacheType.PLAN);
    System.out.println("Plan cache cleared");

    // Clear all (using default)
    client.clearCache();
    System.out.println("All caches cleared (default)");
}

Parser Warmup

warmupParser()

Pre-allocate parser instances for better performance:

Java
public void warmupParsers(GqldbClient client) {
    // Pre-allocate 10 parser instances
    client.warmupParser(10);
    System.out.println("Parsers warmed up");
}

This is useful before high-load periods to reduce latency from parser initialization.

Database Statistics

getStatistics()

Get statistics about the database or a specific graph:

Java
import com.gqldb.services.AdminService;

public void getStats(GqldbClient client) {
    // Get overall database statistics
    AdminService.Statistics dbStats = client.getStatistics();
    System.out.println("Database statistics: " + dbStats);

    // Get statistics for a specific graph
    AdminService.Statistics graphStats = client.getStatistics("myGraph");
    System.out.println("Graph statistics: " + graphStats);
}

Permission Cache

invalidatePermissionCache()

Invalidate the RBAC (Role-Based Access Control) permission cache:

Java
public void invalidatePermissions(GqldbClient client) {
    // Invalidate all permission caches
    client.invalidatePermissionCache();
    System.out.println("All permission caches invalidated");

    // Invalidate cache for a specific user
    client.invalidatePermissionCache("johndoe");
    System.out.println("Permission cache invalidated for johndoe");
}

Use this after changing user permissions to ensure changes take effect immediately.

Complete Example

Java
import com.gqldb.*;
import com.gqldb.types.CacheType;
import com.gqldb.types.HealthStatus;
import com.gqldb.services.AdminService;

public class HealthAdminExample {
    public static void main(String[] args) {
        GqldbConfig config = GqldbConfig.builder()
            .hosts("192.168.1.100:9000")
            .build();

        try (GqldbClient client = new GqldbClient(config)) {
            client.login("admin", "password");

            // Health check
            System.out.println("=== Health Check ===");
            HealthStatus health = client.healthCheck();
            System.out.println("Server status: " + health);

            // Warmup parsers
            System.out.println("\n=== Parser Warmup ===");
            client.warmupParser(5);
            System.out.println("Warmed up 5 parser instances");

            // Execute some queries to populate cache
            System.out.println("\n=== Executing Queries ===");
            client.gql("MATCH (n) RETURN count(n)");
            client.gql("MATCH (n) RETURN count(n)");  // Should hit cache
            client.gql("MATCH (n)-[e]->(m) RETURN count(e)");

            // Check cache stats
            System.out.println("\n=== Cache Statistics ===");
            AdminService.CacheStats cacheStats = client.getCacheStats(CacheType.ALL);
            System.out.println("Cache stats: " + cacheStats);

            // Get database statistics
            System.out.println("\n=== Database Statistics ===");
            AdminService.Statistics dbStats = client.getStatistics();
            System.out.println("Database stats: " + dbStats);

            // Start health monitoring
            System.out.println("\n=== Health Monitoring ===");
            GqldbClient.HealthWatcher watcher = client.watch(status -> {
                System.out.println("Health update: " + status);
            });

            // Let it run for 5 seconds
            Thread.sleep(5000);
            watcher.stop();
            System.out.println("Health monitoring stopped");

            // Clear caches
            System.out.println("\n=== Clear Caches ===");
            client.clearCache(CacheType.ALL);
            System.out.println("All caches cleared");

            // Verify caches are cleared
            AdminService.CacheStats clearedStats = client.getCacheStats(CacheType.ALL);
            System.out.println("Cache stats after clear: " + clearedStats);

            // Invalidate permission cache
            System.out.println("\n=== Permission Cache ===");
            client.invalidatePermissionCache();
            System.out.println("Permission cache invalidated");

        } catch (Exception e) {
            System.err.println("Error: " + e.getMessage());
            e.printStackTrace();
        }
    }
}