rustdb 0.2.3

//! This crate (rustdb) implements a high-performance database written entirely in [Rust](https://www.rust-lang.org/).
//!
//! The SQL-like language is relatively minimal, and does not (currently) include features such as joins or views.
//! Instead it has high performance SET .. FROM ... and FOR .. FROM statements to access database tables,
//! generally using an INDEX.
//!
//! The complete language manual is available at run-time via the pre-configured (but optional) [init::INITSQL]
//! database initialisation string, which also includes many functions which illustrate how the language works,
//! including generic table browsing/editing, date and other functions.
//!
//! Read-only transactions run immediately and concurrently on a virtual read-only copy of the database, and cannot be blocked.
//! Write transactions run sequentially (and should typically execute in around 100 micro-seconds). The [Storage] trait allows a variety of underlying storage, including [SimpleFileStorage], [MemFile] and [AtomicFile].

//!# Interface
//!
//! The method [Database::run] (or alternatively [Database::run_timed]) is called to execute an SQL query.
//! This takes a [Transaction] parameter which accumulates SELECT results and which also has methods
//! for accessing input parameters and controlling output. Custom builtin functions implement [CExp]
//! and have access to the transaction via an [EvalEnv] parameter, which can be downcast if necessary.   
//!
//!# Examples
//! (a) Simple single-threaded web server using SimpleFileStorage as underlying storage.s
//! ```
//! use rustdb::{standard_builtins, AccessPagedData, Database, SharedPagedData, SimpleFileStorage, WebTransaction, INITSQL, BuiltinMap};
//! use std::net::TcpListener;
//! use std::sync::Arc;
//!
//! let sfs = Box::new(SimpleFileStorage::new( "..\\test.rustdb" ));
//! let spd = Arc::new(SharedPagedData::new(sfs));
//! let apd = AccessPagedData::new_writer(spd);
//! let mut bmap = BuiltinMap::new();
//! standard_builtins( &mut bmap );
//! let bmap = Arc::new(bmap);
//! let db = Database::new(apd, INITSQL, bmap);
//!
//! let listener = TcpListener::bind("127.0.0.1:3000").unwrap();
//! for tcps in listener.incoming() {
//!     if let Ok(mut tcps) = tcps {
//!         if let Ok(mut tr) = WebTransaction::new(&tcps) {
//!             // tr.trace();
//!             let sql = "EXEC web.Main()";
//!             // Execute SQL. http response, SQL output, (status,headers,content) is accumulated in wq.
//!             db.run_timed(&sql, &mut tr);
//!             // Write the http response to the TCP stream.
//!             let _err = tr.write(&mut tcps);
//!             // Save database changes to disk.
//!             db.save();
//!         }
//!     }
//! }
//!```
//!
//! (b) [See here](https://github.com/georgebarwood/RustDB/blob/main/examples/axumtest.rs) for more advanced example -
//! an Axum-based webserver using [AtomicFile], the ARGON hash function, read-only queries and query logging.
//!
//!# Features
//!
//! This crate supports two cargo features.
//! - `builtin` : Allows extra SQL builtin functions to be defined.
//! - `max` : Exposes maximal interface, including all internal modules (default).
//!
//!# General Design of Database
//!
//! SortedFile stores fixed size Records in a tree of Pages.
//! SortedFile is used to implement:
//!
//! - Variable length values which are split into fragments - see bytes module - although up to 254 bytes can be stored inline.
//!
//! - Database Table storage. Each record has a 64-bit Id.
//!
//! - Index storage ( an index record refers back to the main table ).
//!
//! When a page becomes too big, it is split into two pages.
//!
//! Each page is implemented as a binary tree ( so there is a tree of trees ).
//!
//! [SharedPagedData] allows logical database pages to be shared to allow concurrent readers.
//!
//! [AtomicFile] ensures that database updates are all or nothing.
//!
//!# ToDo List
//! Decide whether to have several crates : "Core", "Lang", "Server" say.
//! Core being data storage, Lang being SQL-subset, Server being interfacing to http/serde etc.
//!
//! Call web.Main directly ( using function ptr ).
//!
//! Unify GenTransaction and WebTransaction. Check multiple file upload works ok with local http parsing.
//!
//! Implement DROP INDEX, ALTER TABLE, fully implement CREATE INDEX.
//!
//! Implement email in example program. Replication of log files. Server status.
//!
//! Sort out error handling for PARSEINT etc.
//!
//! Work on improving/testing SQL code, browse schema, float I/O. Login.
//!

pub use crate::{
    atomfile::AtomicFile,
    gentrans::{GenTransaction, Part},
    init::INITSQL,
    pstore::{AccessPagedData, SharedPagedData},
    stg::{MemFile, SimpleFileStorage},
    webtrans::WebTransaction,
};

#[cfg(feature = "builtin")]
pub use crate::{
    builtin::check_types,
    builtin::standard_builtins,
    compile::{c_bool, c_float, c_int, c_value},
    exec::EvalEnv,
    expr::{Block, DataKind, Expr},
    run::{CExp, CExpPtr, CompileFunc},
    value::Value,
};
#[cfg(not(feature = "builtin"))]
use crate::{
    compile::{c_bool, c_int, c_value},
    exec::EvalEnv,
    expr::{Block, DataKind, Expr},
    run::{CExp, CExpPtr, CompileFunc},
    value::Value,
};

use crate::{
    bytes::ByteStorage,
    compact::CompactFile,
    expr::*,
    page::{Page, PagePtr},
    parse::Parser,
    run::*,
    sortedfile::{Asc, Id, Record, SortedFile},
    stg::Storage,
    table::{ColInfo, IndexInfo, Row, SaveOp, Table, TablePtr},
    util::{nd, newmap, SmallSet},
    value::*,
};

use std::{
    cell::{Cell, RefCell},
    cmp::Ordering,
    collections::{BTreeMap, BTreeSet, HashMap, HashSet},
    panic,
    rc::Rc,
    sync::{Arc, Mutex, RwLock},
};

/// Utility functions and macros, [SmallSet].
#[cfg(feature = "max")]
#[macro_use]
pub mod util;
#[cfg(not(feature = "max"))]
#[macro_use]
mod util;

// Modules that are always public.

/// [GenTransaction] ( implementation of [Transaction] ).
pub mod gentrans;

/// [WebTransaction] ( alternative implementation of [Transaction] with http support ).
pub mod webtrans;

/// Initial SQL.
///
/// Note : the [init::INITSQL] string can be generated using the "Script entire database" link in the runtime main menu,
/// then using an editor to escape every `"` character as `\"`.
pub mod init;

/// Backing [Storage] for database. See also [AtomicFile].
pub mod stg;

/// Page storage and sharing, [SharedPagedData] and [AccessPagedData]
pub mod pstore;

/// [AtomicFile]
pub mod atomfile;

// Conditional modules.

// #[cfg(target_os = "windows")]
// Optimised implementatation of [Storage] (windows only).
// This didn't work out - actually ran slower!
// pub mod stgwin;

#[cfg(feature = "max")]
/// Compilation of builtin functions.
pub mod builtin;
#[cfg(not(feature = "max"))]
mod builtin;

#[cfg(feature = "max")]
/// Storage of variable length values : [ByteStorage].
pub mod bytes;
#[cfg(not(feature = "max"))]
mod bytes;

#[cfg(feature = "max")]
/// Structs that implement [CExp] trait.
pub mod cexp;
#[cfg(not(feature = "max"))]
mod cexp;

#[cfg(feature = "max")]
/// [CompactFile] : storage of logical pages in smaller regions of backing storage.
pub mod compact;
#[cfg(not(feature = "max"))]
mod compact;

#[cfg(feature = "builtin")]
/// Functions to compile parsed expressions, checking types.
pub mod compile;
#[cfg(not(feature = "builtin"))]
mod compile;

#[cfg(feature = "max")]
/// [EvalEnv] : [Instruction] execution.
pub mod exec;
#[cfg(not(feature = "max"))]
mod exec;

#[cfg(feature = "builtin")]
/// Expression types, result of parsing. [Expr].
pub mod expr;
#[cfg(not(feature = "builtin"))]
mod expr;

#[cfg(feature = "max")]
/// [Page] for [SortedFile].
pub mod page;
#[cfg(not(feature = "max"))]
mod page;

#[cfg(feature = "max")]
/// [Parser].
pub mod parse;
#[cfg(not(feature = "max"))]
mod parse;

#[cfg(feature = "max")]
/// [Instruction] and other run time types.
pub mod run;
#[cfg(not(feature = "max"))]
mod run;

#[cfg(feature = "max")]
/// [SortedFile] : [Record] storage.
pub mod sortedfile;
#[cfg(not(feature = "max"))]
mod sortedfile;

#[cfg(feature = "max")]
/// System table functions.
pub mod sys;
#[cfg(not(feature = "max"))]
mod sys;

#[cfg(feature = "max")]
/// [Table], [ColInfo], [Row] and other Table types.
pub mod table;
#[cfg(not(feature = "max"))]
mod table;

#[cfg(feature = "builtin")]
/// Run-time [Value].
pub mod value;
#[cfg(not(feature = "builtin"))]
mod value;

// End of modules.

/// ```Arc<Vec<u8>>```
pub type Data = Arc<Vec<u8>>;

/// ```Rc<Database>```
pub type DB = Rc<Database>;

/// Map that defines SQL pre-defined functions.
pub type BuiltinMap = HashMap<String, (DataKind, CompileFunc)>;

/// Database with SQL-like interface.
pub struct Database {
    /// Page storage.
    pub file: AccessPagedData,
    // System tables.
    pub sys_schema: TablePtr,
    pub sys_table: TablePtr,
    pub sys_column: TablePtr,
    pub sys_index: TablePtr,
    pub sys_index_col: TablePtr,
    pub sys_function: TablePtr,
    /// Storage of variable length data.
    pub bs: ByteStorage,
    // Various maps for named database objects.
    pub schemas: RefCell<HashMap<String, i64>>,
    pub tables: RefCell<HashMap<ObjRef, TablePtr>>,
    pub functions: RefCell<HashMap<ObjRef, FunctionPtr>>,
    pub builtins: Arc<BuiltinMap>,
    /// Flag to reset the functions cache after save.
    pub function_reset: Cell<bool>,
    /// Last id generated by INSERT.
    pub lastid: Cell<i64>,
    /// Has there been an error since last save?
    pub err: Cell<bool>,
}

impl Database {
    /// Construct a new DB, based on the specified file.
    /// initsql is used to initialised a new database.
    /// builtins specifies the functions callable in SQL code such as SUBSTR, REPLACE etc.
    pub fn new(file: AccessPagedData, initsql: &str, builtins: Arc<BuiltinMap>) -> DB {
        let mut dq = DummyTransaction {};
        let is_new = file.is_new();
        let mut tb = TableBuilder::new();
        let sys_schema = tb.nt("Schema", &[("Name", STRING)]);
        let sys_table = tb.nt(
            "Table",
            &[
                ("Root", INT),
                ("Schema", INT),
                ("Name", STRING),
                ("IdGen", INT),
            ],
        );
        let sys_column = tb.nt("Column", &[("Table", INT), ("Name", STRING), ("Type", INT)]);
        let sys_index = tb.nt("Index", &[("Root", INT), ("Table", INT), ("Name", STRING)]);
        let sys_index_col = tb.nt("IndexColumn", &[("Index", INT), ("ColId", INT)]);
        let sys_function = tb.nt(
            "Function",
            &[("Schema", INT), ("Name", STRING), ("Def", BIGSTR)],
        );
        sys_schema.add_index(7, vec![0]);
        sys_table.add_index(8, vec![1, 2]);
        sys_column.add_index(9, vec![0]);
        sys_index.add_index(10, vec![1]);
        sys_index_col.add_index(11, vec![0]);
        sys_function.add_index(12, vec![0, 1]);

        let db = Rc::new(Database {
            file,
            sys_schema,
            sys_table,
            sys_column,
            sys_index,
            sys_index_col,
            sys_function,
            bs: ByteStorage::new(0),
            schemas: newmap(),
            functions: newmap(),
            tables: newmap(),
            builtins,
            function_reset: Cell::new(false),
            lastid: Cell::new(0),
            err: Cell::new(false),
        });
        if is_new {
            db.alloc_page(); // Allocate page for byte storage.
        }
        db.bs.init(&db);
        for t in &tb.list {
            if !is_new {
                t.id_gen.set(sys::get_id_gen(&db, t.id as u64));
            }
            db.publish_table(t.clone());
        }
        if is_new {
            // The creation order has to match the order above ( so root values are as predicted ).
            let sysinit = "
CREATE SCHEMA sys
GO
CREATE TABLE sys.Schema( Name string )
CREATE TABLE sys.Table( Root int, Schema int, Name string, IdGen int )
CREATE TABLE sys.Column( Table int, Name string, Type int )
CREATE TABLE sys.Index( Root int, Table int, Name string )
CREATE TABLE sys.IndexColumn( Index int, ColId int )
CREATE TABLE sys.Function( Schema int, Name string, Def string(249) )
GO
CREATE INDEX ByName ON sys.Schema(Name)
CREATE INDEX BySchemaName ON sys.Table(Schema,Name)
CREATE INDEX ByTable ON sys.Column(Table)
CREATE INDEX ByTable ON sys.Index(Table)
CREATE INDEX ByIndex ON sys.IndexColumn(Index)
CREATE INDEX BySchemaName ON sys.Function(Schema,Name)
GO
";
            db.run(sysinit, &mut dq);
            db.run(initsql, &mut dq);
            db.save();
        }
        db
    }

    /// Run a batch of SQL.
    pub fn run(self: &DB, source: &str, tr: &mut dyn Transaction) {
        if let Some(e) = self.go(source, tr) {
            let err = format!(
                "{} in {} at line {} column {}.",
                e.msg, e.rname, e.line, e.column
            );
            println!("Run error {}", &err);
            tr.set_error(err);
            self.err.set(true);
        }
    }
    /// Run a batch of SQL, printing the execution time.
    pub fn run_timed(self: &DB, source: &str, tr: &mut dyn Transaction) {
        let start = std::time::Instant::now();
        self.run(source, tr);
        println!(
            "run_timed path={} run time={} micro sec.",
            tr.arg(0, ""),
            start.elapsed().as_micros()
        );
    }

    /// Run a batch of SQL.
    pub(crate) fn go(self: &DB, source: &str, tr: &mut dyn Transaction) -> Option<SqlError> {
        let mut p = Parser::new(source, self);
        let result = std::panic::catch_unwind(panic::AssertUnwindSafe(|| {
            p.batch(tr);
        }));
        if let Err(x) = result {
            Some(if let Some(e) = x.downcast_ref::<SqlError>() {
                SqlError {
                    msg: e.msg.clone(),
                    line: e.line,
                    column: e.column,
                    rname: e.rname.clone(),
                }
            } else if let Some(s) = x.downcast_ref::<&str>() {
                p.make_error((*s).to_string())
            } else if let Some(s) = x.downcast_ref::<String>() {
                p.make_error(s.to_string())
            } else {
                p.make_error("unrecognised/unexpected error".to_string())
            })
        } else {
            None
        }
    }

    /// Save updated tables to underlying file ( or rollback if there was an error ).
    /// Returns the number of logical pages that were updated.
    pub fn save(self: &DB) -> usize {
        let op = if self.err.get() {
            self.err.set(false);
            SaveOp::RollBack
        } else {
            SaveOp::Save
        };
        self.bs.save(self, op);
        let tm = &*self.tables.borrow();
        for t in tm.values() {
            if t.id_gen_dirty.get() {
                if op == SaveOp::Save {
                    sys::save_id_gen(self, t.id as u64, t.id_gen.get());
                } else {
                    t.id_gen.set(sys::get_id_gen(self, t.id as u64));
                }
                t.id_gen_dirty.set(false);
            }
        }
        for t in tm.values() {
            t.save(self, op);
        }
        if self.function_reset.get() {
            for function in self.functions.borrow().values() {
                function.ilist.borrow_mut().clear();
            }
            self.functions.borrow_mut().clear();
            self.function_reset.set(false);
        }
        self.file.save(op)
    }

    /// Get the named table.
    pub fn get_table(self: &DB, name: &ObjRef) -> Option<TablePtr> {
        if let Some(t) = self.tables.borrow().get(name) {
            return Some(t.clone());
        }
        sys::get_table(self, name)
    }

    /// Get the named function.
    pub(crate) fn get_function(self: &DB, name: &ObjRef) -> Option<FunctionPtr> {
        if let Some(f) = self.functions.borrow().get(name) {
            return Some(f.clone());
        }
        sys::get_function(self, name)
    }

    /// Insert the table into the map of tables.
    pub(crate) fn publish_table(&self, table: TablePtr) {
        let name = table.info.name.clone();
        self.tables.borrow_mut().insert(name, table);
    }

    /// Get code for value.
    pub(crate) fn encode(self: &DB, val: &Value, size: usize) -> u64 {
        let bytes = match val {
            Value::RcBinary(x) => &**x,
            Value::ArcBinary(x) => &**x,
            Value::String(x) => x.as_bytes(),
            _ => {
                return u64::MAX;
            }
        };
        if bytes.len() < size {
            return u64::MAX;
        }
        self.bs.encode(self, &bytes[size - 9..])
    }

    /// Decode u64 to bytes.
    pub(crate) fn decode(self: &DB, code: u64, inline: usize) -> Vec<u8> {
        self.bs.decode(self, code, inline)
    }

    /// Delete encoding.
    pub(crate) fn delcode(self: &DB, code: u64) {
        self.bs.delcode(self, code);
    }

    /// Allocate a page of underlying file storage.
    pub(crate) fn alloc_page(self: &DB) -> u64 {
        self.file.alloc_page()
    }

    /// Free a page of underyling file storage.
    pub(crate) fn free_page(self: &DB, lpnum: u64) {
        self.file.free_page(lpnum);
    }
} // end impl Database

impl Drop for Database {
    /// Clear function instructions to avoid leaking memory.
    fn drop(&mut self) {
        for function in self.functions.borrow().values() {
            function.ilist.borrow_mut().clear();
        }
    }
}

/// For creating system tables.
struct TableBuilder {
    alloc: i64,
    list: Vec<TablePtr>,
}
impl TableBuilder {
    fn new() -> Self {
        Self {
            alloc: 1,
            list: Vec::new(),
        }
    }
    fn nt(&mut self, name: &str, ct: &[(&str, DataType)]) -> TablePtr {
        let id = self.alloc;
        let root_page = id as u64;
        self.alloc += 1;
        let name = ObjRef::new("sys", name);
        let info = ColInfo::new(name, ct);
        let table = Table::new(id, root_page, 1, Rc::new(info));
        self.list.push(table.clone());
        table
    }
}

/// Input/Output message. Query and Response.
pub trait Transaction: std::any::Any {
    /// STATUSCODE builtin function. sets the response status code.
    fn status_code(&mut self, _code: i64) {}

    /// HEADER builtin function, adds header to response.
    fn header(&mut self, _name: &str, _value: &str) {}

    /// Append SELECT values to response body.
    fn selected(&mut self, values: &[Value]);

    /// GLOBAL builtin function. Used to get request time.
    fn global(&self, _kind: i64) -> i64 {
        0
    }

    /// ARG builtin function. Get path, query parameter, form value or cookie.
    fn arg(&mut self, _kind: i64, _name: &str) -> Rc<String> {
        Rc::new(String::new())
    }

    /// Get file attribute ( One of name, content_type, file_name )
    fn file_attr(&mut self, _fnum: i64, _atx: i64) -> Rc<String> {
        Rc::new(String::new())
    }

    /// Get file content.
    fn file_content(&mut self, _fnum: i64) -> Arc<Vec<u8>> {
        nd()
    }

    /// Set the error string.
    fn set_error(&mut self, err: String);

    /// Get the error string.
    fn get_error(&mut self) -> String {
        String::new()
    }
}

/// Query where output is printed to console (used for initialisation ).
struct DummyTransaction {}
impl Transaction for DummyTransaction {
    fn selected(&mut self, _values: &[Value]) {}
    /// Called if a panic ( error ) occurs.
    fn set_error(&mut self, err: String) {
        println!("Error: {}", err);
    }
}