membase 0.2.1

Ultra-high performance async runtime with fast task cycling, lock-free scheduling, and zero-overhead performance
Documentation 
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//! Storage management for columnar database.
#![allow(unused_variables)]
use std::path::PathBuf;

use crate::error::{Error, Result};
use crate::columnar::schema::Schema;
use crate::columnar::table::Table;
use crate::columnar::compression::CompressionType;

/// Storage options for the columnar database.
#[derive(Debug, Clone)]
pub struct StorageOptions {
    /// Base directory for database files
    pub base_dir: PathBuf,
    
    /// Compression type to use for columns
    pub compression: CompressionType,
    
    /// Whether to create directories if they don't exist
    pub create_dirs: bool,
    
    /// Whether to use memory mapping for files
    pub use_mmap: bool,
}

impl Default for StorageOptions {
    fn default() -> Self {
        StorageOptions {
            base_dir: PathBuf::from("db"),
            compression: CompressionType::None,
            create_dirs: true,
            use_mmap: true,
        }
    }
}

/// Storage manager for the columnar database.
pub struct Storage {
    /// Storage options
    options: StorageOptions,
}

impl Storage {
    /// Create a new storage manager.
    pub fn new(options: StorageOptions) -> Result<Self> {
        // Create base directory if it doesn't exist
        if options.create_dirs && !options.base_dir.exists() {
            std::fs::create_dir_all(&options.base_dir)?;
        }
        
        Ok(Storage {
            options,
        })
    }
    
    /// Create a new table.
    pub fn create_table(&self, name: &str, schema: Schema) -> Result<Table> {
        let table_dir = self.options.base_dir.join(name);
        
        // Check if the table already exists
        if table_dir.exists() {
            return Err(Error::InvalidArgument(format!(
                "Table {} already exists",
                name
            )));
        }
        
        // Create table directory
        std::fs::create_dir_all(&table_dir)?;
        
        // Write schema to file
        // In a real implementation, we would serialize the schema to JSON
        // For this example, we'll skip this step
        
        // Create empty column files
        for field in &schema.fields {
            let column_path = table_dir.join(format!("{}.col", field.name));
            let mut _file = std::fs::File::create(column_path)?;
            // Write an empty column header
            // In a real implementation, we would write a proper header
            // For this example, we'll skip this step
        }
        
        // Open the table
        Table::open(name, self.options.base_dir.to_str().unwrap())
    }
    
    /// Open an existing table.
    pub fn open_table(&self, name: &str) -> Result<Table> {
        Table::open(name, self.options.base_dir.to_str().unwrap())
    }
    
    /// Drop a table.
    pub fn drop_table(&self, name: &str) -> Result<()> {
        let table_dir = self.options.base_dir.join(name);
        
        // Check if the table exists
        if !table_dir.exists() {
            return Err(Error::InvalidArgument(format!(
                "Table {} does not exist",
                name
            )));
        }
        
        // Remove the table directory and all its contents
        std::fs::remove_dir_all(table_dir)?;
        
        Ok(())
    }
    
    /// List all tables.
    pub fn list_tables(&self) -> Result<Vec<String>> {
        let mut tables = Vec::new();
        
        for entry in std::fs::read_dir(&self.options.base_dir)? {
            let entry = entry?;
            let path = entry.path();
            
            if path.is_dir() {
                if let Some(name) = path.file_name() {
                    if let Some(name_str) = name.to_str() {
                        tables.push(name_str.to_string());
                    }
                }
            }
        }
        
        Ok(tables)
    }
    
    /// Get the storage options.
    pub fn options(&self) -> &StorageOptions {
        &self.options
    }
}