# SlidingSQLite Usage Documentation

This document provides detailed instructions on how to use the `SlidingSQLite` library, including its API, configuration options, and best practices.

## Table of Contents

1. [Overview](#overview)
2. [Installation](#installation)
3. [Configuration](#configuration)
4. [Basic Usage](#basic-usage)
   - [Initializing the Database](#initializing-the-database)
   - [Executing Write Queries](#executing-write-queries)
   - [Executing Read Queries](#executing-read-queries)
   - [Retrieving Results](#retrieving-results)
   - [Shutting Down](#shutting-down)
5. [Advanced Usage](#advanced-usage)
   - [Multi-Threaded Applications](#multi-threaded-applications)
   - [Managing Database Retention](#managing-database-retention)
   - [Customizing Cleanup](#customizing-cleanup)
   - [Querying Across Time Windows](#querying-across-time-windows)
6. [API Reference](#api-reference)
7. [Error Handling](#error-handling)
8. [Best Practices](#best-practices)
9. [Example](#example)

## Overview

`SlidingSQLite` is a thread-safe SQLite wrapper that supports time-based database rotation, making it ideal for applications that need to manage time-series data or logs with automatic cleanup. It provides asynchronous query execution, automatic database rotation, and retention policies, all while ensuring thread safety through a queue-based worker system.

## Installation

To use `SlidingSQLite`, ensure you have Python 3.7 or higher installed. The library uses only the standard library and SQLite, which is included with Python.

1. Copy the `SlidingSqlite.py` file into your project directory.
2. Import the `SlidingSQLite` class in your Python code:
   ```python
   from SlidingSqlite import SlidingSQLite
   ```

## Configuration

The `SlidingSQLite` class is initialized with several configuration parameters:

- **`db_dir`**: Directory where database files will be stored.
- **`schema`**: SQL schema to initialize new database files (e.g., table definitions).
- **`rotation_interval`**: Time interval (in seconds) after which a new database file is created (default: 3600 seconds, or 1 hour).
- **`retention_period`**: Time period (in seconds) to retain database files before deletion (default: 604800 seconds, or 7 days).
- **`cleanup_interval`**: Frequency (in seconds) of the cleanup process for old databases and stale queries (default: 3600 seconds, or 1 hour).
- **`auto_delete_old_dbs`**: Boolean flag to enable or disable automatic deletion of old databases (default: `True`).

Example configuration:

```python
schema = """
CREATE TABLE IF NOT EXISTS logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp REAL,
    message TEXT
);
"""

db = SlidingSQLite(
    db_dir="./databases",
    schema=schema,
    rotation_interval=3600,  # Rotate every hour
    retention_period=604800,  # Keep databases for 7 days
    cleanup_interval=3600,   # Run cleanup every hour
    auto_delete_old_dbs=True
)
```

## Basic Usage

### Initializing the Database

Create an instance of `SlidingSQLite` with your desired configuration. This will set up the database directory, initialize the metadata database, and start the background workers for write operations and cleanup.

```python
from SlidingSqlite import SlidingSQLite
import logging

logging.basicConfig(level=logging.INFO)

schema = """
CREATE TABLE IF NOT EXISTS logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp REAL,
    message TEXT
);
"""

db = SlidingSQLite(
    db_dir="./databases",
    schema=schema
)
```

### Executing Write Queries

Use the `execute_write` method to perform write operations (e.g., `INSERT`, `UPDATE`, `DELETE`). This method is asynchronous and returns a UUID that can be used to retrieve the result.

```python
import time

query_id = db.execute_write(
    "INSERT INTO logs (timestamp, message) VALUES (?, ?)",
    (time.time(), "Hello, SlidingSQLite!")
)
```

For synchronous execution, use `execute_write_sync`, which blocks until the operation completes or times out:

```python
result = db.execute_write_sync(
    "INSERT INTO logs (timestamp, message) VALUES (?, ?)",
    (time.time(), "Synchronous write"),
    timeout=5.0
)
if result.success:
    logging.info("Write operation successful")
else:
    logging.error(f"Write operation failed: {result.error}")
```

### Executing Read Queries

Use the `execute_read` method to perform read operations (e.g., `SELECT`). This method executes the query across all relevant database files, providing a seamless view of time-windowed data. It is asynchronous and returns a UUID.

```python
query_id = db.execute_read(
    "SELECT * FROM logs WHERE timestamp > ? ORDER BY timestamp DESC",
    (time.time() - 86400,)  # Last 24 hours
)
```

For synchronous execution, use `execute_read_sync`:

```python
result = db.execute_read_sync(
    "SELECT * FROM logs WHERE timestamp > ? ORDER BY timestamp DESC",
    (time.time() - 86400,),
    timeout=5.0
)
if result.success:
    logging.info(f"Found {len(result.data)} log entries: {result.data}")
else:
    logging.error(f"Read operation failed: {result.error}")
```

### Retrieving Results

For asynchronous operations, use `get_result` (for write queries) or `get_read_result` (for read queries) to retrieve the results using the UUID returned by `execute_write` or `execute_read`.

```python
# Write result
result = db.get_result(query_id, timeout=5.0)
if result.success:
    logging.info("Write operation successful")
else:
    logging.error(f"Write operation failed: {result.error}")

# Read result
result = db.get_read_result(query_id, timeout=5.0)
if result.success:
    logging.info(f"Found {len(result.data)} log entries: {result.data}")
else:
    logging.error(f"Read operation failed: {result.error}")
```

### Shutting Down

Always call the `shutdown` method when you are done with the database to ensure graceful cleanup of resources:

```python
db.shutdown()
```

## Advanced Usage

### Multi-Threaded Applications

`SlidingSQLite` is designed for multi-threaded environments. It uses queues and locks to ensure thread safety. Here is an example of using multiple writer and reader threads:

```python
import threading
import time
import random
from SlidingSqlite import SlidingSQLite
import logging

logging.basicConfig(level=logging.INFO)

schema = """
CREATE TABLE IF NOT EXISTS logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp REAL,
    message TEXT
);
"""

db = SlidingSQLite(
    db_dir="./databases",
    schema=schema,
    rotation_interval=10,  # Rotate every 10 seconds for testing
    retention_period=60,   # Keep databases for 60 seconds
    cleanup_interval=30    # Run cleanup every 30 seconds
)

def writer_thread():
    while True:
        db.execute_write(
            "INSERT INTO logs (timestamp, message) VALUES (?, ?)",
            (time.time(), f"Message from thread {threading.current_thread().name}")
        )
        time.sleep(random.uniform(0.05, 0.15))

def reader_thread():
    while True:
        result = db.execute_read_sync(
            "SELECT * FROM logs ORDER BY timestamp DESC LIMIT 5",
            timeout=5.0
        )
        if result.success:
            logging.info(f"Recent logs: {result.data}")
        time.sleep(random.uniform(0.5, 1.5))

threads = []
for _ in range(4):  # Start 4 writer threads
    t = threading.Thread(target=writer_thread, daemon=True)
    t.start()
    threads.append(t)
for _ in range(2):  # Start 2 reader threads
    t = threading.Thread(target=reader_thread, daemon=True)
    t.start()
    threads.append(t)

try:
    while True:
        time.sleep(1)
except KeyboardInterrupt:
    print("\nShutting down...")
    db.shutdown()
```

### Managing Database Retention

You can configure the retention period and control database deletion:

- **Set Retention Period**: Use `set_retention_period` to change how long databases are kept:

  ```python
  db.set_retention_period(86400)  # Keep databases for 1 day
  ```

- **Enable/Disable Auto-Delete**: Use `set_auto_delete` to control automatic deletion of old databases:

  ```python
  db.set_auto_delete(False)  # Disable automatic deletion
  ```

- **Manual Deletion**: Use `delete_databases_before` or `delete_databases_in_range` to manually delete databases:

  ```python
  import time

  # Delete all databases before a specific timestamp
  count = db.delete_databases_before(time.time() - 86400)
  logging.info(f"Deleted {count} databases")

  # Delete databases in a specific time range
  count = db.delete_databases_in_range(time.time() - 172800, time.time() - 86400)
  logging.info(f"Deleted {count} databases in range")
  ```

### Customizing Cleanup

You can adjust the cleanup interval to control how often the system checks for old databases and stale queries:

```python
db = SlidingSQLite(
    db_dir="./databases",
    schema=schema,
    cleanup_interval=1800  # Run cleanup every 30 minutes
)
```

### Querying Across Time Windows

Read queries are automatically executed across all relevant database files, providing a unified view of data across time windows. This is particularly useful for time-series data or logs. For example:

```python
result = db.execute_read_sync(
    "SELECT timestamp, message FROM logs WHERE timestamp > ? ORDER BY timestamp DESC",
    (time.time() - 604800,)  # Last 7 days
)
if result.success:
    logging.info(f"Found {len(result.data)} log entries: {result.data}")
```

## API Reference

### `SlidingSQLite` Class

#### Initialization

```python
SlidingSQLite(
    db_dir: str,
    schema: str,
    retention_period: int = 604800,
    rotation_interval: int = 3600,
    cleanup_interval: int = 3600,
    auto_delete_old_dbs: bool = True
)
```

- **Parameters**:
  - `db_dir`: Directory to store database files.
  - `schema`: SQL schema to initialize new databases.
  - `retention_period`: Seconds to keep databases before deletion.
  - `rotation_interval`: Seconds between database rotations.
  - `cleanup_interval`: Seconds between cleanup operations.
  - `auto_delete_old_dbs`: Whether to automatically delete old databases.

#### Methods

- **`execute(query: str, params: Tuple[Any, ...] = ()) -> uuid.UUID`**:
  Smart query executor that routes read or write operations appropriately.

- **`execute_write(query: str, params: Tuple[Any, ...] = ()) -> uuid.UUID`**:
  Execute a write query asynchronously. Returns a UUID for result retrieval.

- **`execute_write_sync(query: str, params: Tuple[Any, ...] = (), timeout: float = 5.0) -> QueryResult[bool]`**:
  Execute a write query synchronously. Returns a `QueryResult` object.

- **`execute_read(query: str, params: Tuple[Any, ...] = ()) -> uuid.UUID`**:
  Execute a read query asynchronously across all databases. Returns a UUID.

- **`execute_read_sync(query: str, params: Tuple[Any, ...] = (), timeout: float = 5.0) -> QueryResult[List[Tuple[Any, ...]]]`**:
  Execute a read query synchronously across all databases. Returns a `QueryResult`.

- **`get_result(query_id: uuid.UUID, timeout: float = 5.0) -> QueryResult[bool]`**:
  Retrieve the result of a write query using its UUID.

- **`get_read_result(query_id: uuid.UUID, timeout: float = 5.0) -> QueryResult[List[Tuple[Any, ...]]]`**:
  Retrieve the result of a read query using its UUID.

- **`set_retention_period(seconds: int) -> None`**:
  Set the retention period for databases.

- **`set_auto_delete(enabled: bool) -> None`**:
  Enable or disable automatic deletion of old databases.

- **`delete_databases_before(timestamp: float) -> int`**:
  Delete all databases with `end_time` before the specified timestamp. Returns the number of databases deleted.

- **`delete_databases_in_range(start_time: float, end_time: float) -> int`**:
  Delete all databases overlapping with the specified time range. Returns the number of databases deleted.

- **`get_databases_info() -> List[DatabaseTimeframe]`**:
  Get information about all available databases, including file paths and time ranges.

- **`shutdown() -> None`**:
  Gracefully shut down the database, stopping workers and closing connections.

### `QueryResult` Class

A generic class to handle query results with error handling.

- **Attributes**:
  - `data`: The result data (if successful).
  - `error`: The exception (if failed).
  - `success`: Boolean indicating if the query was successful.

- **Usage**:
  ```python
  result = db.execute_write_sync("INSERT INTO logs (timestamp, message) VALUES (?, ?)", (time.time(), "Test"))
  if result.success:
      print("Success:", result.data)
  else:
      print("Error:", result.error)
  ```

### Exceptions

- **`DatabaseError`**: Base exception for all database errors.
- **`QueryError`**: Exception raised when a query fails.

## Error Handling

`SlidingSQLite` provides robust error handling through the `QueryResult` class and custom exceptions. Always check the `success` attribute of a `QueryResult` object and handle potential errors:

```python
result = db.execute_read_sync("SELECT * FROM logs", timeout=5.0)
if result.success:
    print("Data:", result.data)
else:
    print("Error:", result.error)
```

Common errors include:

- **Query Timeout**: If a query takes longer than the specified timeout, a `QueryError` with "Query timed out" is returned.
- **Invalid Query ID**: Attempting to retrieve results with an invalid UUID results in a `QueryError`.
- **Database Errors**: SQLite errors are wrapped in `DatabaseError` or `QueryError`.

## Best Practices

1. **Always Shut Down**: Call `db.shutdown()` when your application exits to ensure resources are cleaned up properly.
2. **Use Timeouts**: Specify appropriate timeouts for synchronous operations to avoid blocking indefinitely.
3. **Handle Errors**: Always check the `success` attribute of `QueryResult` objects and handle errors appropriately.
4. **Configure Retention**: Choose a retention period that balances disk usage and data availability needs.
5. **Monitor Disk Space**: Even with automatic cleanup, monitor disk space usage in production environments.
6. **Thread Safety**: Use `SlidingSQLite` in multi-threaded applications without additional synchronization, as it is thread-safe by design.
7. **Optimize Queries**: For read operations across many databases, optimize your queries to reduce execution time, especially if the number of database files is large.

## Example

Here is a complete example demonstrating multi-threaded usage, including configuration, query execution, and cleanup:

```python
import time
import uuid
import threading
import random
from datetime import datetime, timezone
from SlidingSqlite import SlidingSQLite
import logging

# Set up logging
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s - %(levelname)s - %(message)s",
    handlers=[logging.StreamHandler()],
)

# Configuration
NUM_WRITER_THREADS = 4
NUM_READER_THREADS = 2
TARGET_OPS_PER_SECOND = 10

# Define a schema
db_schema = """
CREATE TABLE IF NOT EXISTS logs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    timestamp REAL,
    message TEXT
);
"""

# Initialize SlidingSQLite
db = SlidingSQLite(
    db_dir="./databases",
    schema=db_schema,
    rotation_interval=10,  # Rotate every 10 seconds for testing
    retention_period=60,   # Keep databases for 60 seconds
    cleanup_interval=30,   # Run cleanup every 30 seconds
    auto_delete_old_dbs=True,
)

def writer_thread():
    while True:
        db.execute_write(
            "INSERT INTO logs (timestamp, message) VALUES (?, ?)",
            (time.time(), f"Message from thread {threading.current_thread().name}")
        )
        time.sleep(random.uniform(0.05, 0.15))  # Target ~10 ops/sec

def reader_thread():
    while True:
        result = db.execute_read_sync(
            "SELECT * FROM logs ORDER BY timestamp DESC LIMIT 5",
            timeout=5.0
        )
        if result.success:
            logging.info(f"Recent logs: {result.data}")
        time.sleep(random.uniform(0.5, 1.5))  # Randomized sleep for natural load

# Start threads
threads = []
for _ in range(NUM_WRITER_THREADS):
    t = threading.Thread(target=writer_thread, daemon=True)
    t.start()
    threads.append(t)
for _ in range(NUM_READER_THREADS):
    t = threading.Thread(target=reader_thread, daemon=True)
    t.start()
    threads.append(t)

try:
    print("Running multi-threaded SlidingSQLite test. Press Ctrl+C to stop.")
    while True:
        time.sleep(1)
except KeyboardInterrupt:
    print("\nShutting down...")
    db.shutdown()
```

This example demonstrates how to set up a multi-threaded application with `SlidingSQLite`, including logging, configuration, and proper shutdown handling.