core: allocate 2 registers for checkpoint opcode execution

cli/tests/test_journal.rs

@@ -4,7 +4,7 @@
 mod tests {
     use assert_cmd::cargo::cargo_bin;
     use rexpect::error::*;
-    use rexpect::session::spawn_command;
+    use rexpect::session::{spawn_command, PtySession};
     use std::process;
 
     #[test]
@@ -14,9 +14,7 @@ mod tests {
         child.exp_regex(".?")?;
         child.send_line("pragma journal_mode;")?;
         child.exp_string("wal")?;
-        child.send_line(".quit")?;
-        child.exp_eof()?;
-        Ok(())
+        quit(&mut child)
     }
 
     #[test]
@@ -26,14 +24,18 @@ mod tests {
         child.exp_regex(".?")?;
         child.send_line("pragma wal_checkpoint;")?;
         child.exp_string("0|0|0")?;
+        quit(&mut child)
+    }
+
+    fn quit(child: &mut PtySession) -> Result<(), Error> {
         child.send_line(".quit")?;
         child.exp_eof()?;
         Ok(())
     }
 
     fn run_cli() -> process::Command {
         let bin_path = cargo_bin("limbo");
-        let mut cmd = process::Command::new(bin_path);
+        let cmd = process::Command::new(bin_path);
         cmd
     }
 }

core/translate/mod.rs

@@ -25,6 +25,7 @@ pub(crate) mod subquery;
 use crate::schema::Schema;
 use crate::storage::pager::Pager;
 use crate::storage::sqlite3_ondisk::{DatabaseHeader, MIN_PAGE_CACHE_SIZE};
+use crate::storage::wal::CheckpointMode;
 use crate::translate::delete::translate_delete;
 use crate::util::PRIMARY_KEY_AUTOMATIC_INDEX_NAME_PREFIX;
 use crate::vdbe::builder::CursorType;
@@ -37,7 +38,6 @@ use std::cell::RefCell;
 use std::fmt::Display;
 use std::rc::{Rc, Weak};
 use std::str::FromStr;
-use crate::storage::wal::CheckpointMode;
 
 /// Translate SQL statement into bytecode program.
 pub fn translate(
@@ -594,7 +594,7 @@ fn update_pragma(
             Ok(())
         }
         PragmaName::WalCheckpoint => {
-            // TODO
+            query_pragma("wal_checkpoint", header, program)?;
             Ok(())
         }
     }
@@ -616,26 +616,38 @@ fn query_pragma(
                 value: database_header.borrow().default_page_cache_size.into(),
                 dest: register,
             });
+            program.emit_insn(Insn::ResultRow {
+                start_reg: register,
+                count: 1,
+            });
         }
         PragmaName::JournalMode => {
             program.emit_insn(Insn::String8 {
                 value: "wal".into(),
                 dest: register,
             });
+            program.emit_insn(Insn::ResultRow {
+                start_reg: register,
+                count: 1,
+            });
         }
         PragmaName::WalCheckpoint => {
+            // Checkpoint uses 3 registers: P1, P2, P3. Ref Insn::Checkpoint for more info.
+            // Allocate two more here as one was allocated at the top.
+            program.alloc_register();
+            program.alloc_register();
             program.emit_insn(Insn::Checkpoint {
                 database: 0,
                 checkpoint_mode: CheckpointMode::Passive,
                 dest: register,
             });
+            program.emit_insn(Insn::ResultRow {
+                start_reg: register,
+                count: 3,
+            });
         }
     }
 
-    program.emit_insn(Insn::ResultRow {
-        start_reg: register,
-        count: 1,
-    });
     Ok(())
 }
 

core/vdbe/explain.rs

@@ -2,7 +2,6 @@ use crate::vdbe::builder::CursorType;
 
 use super::{Insn, InsnReference, OwnedValue, Program};
 use std::rc::Rc;
-use crate::storage::wal::CheckpointMode;
 
 pub fn insn_to_str(
     program: &Program,
@@ -85,7 +84,11 @@ pub fn insn_to_str(
                 0,
                 format!("r[{}]=~r[{}]", dest, reg),
             ),
-            Insn::Checkpoint { database, checkpoint_mode: _, dest } => (
+            Insn::Checkpoint {
+                database,
+                checkpoint_mode: _,
+                dest,
+            } => (
                 "Checkpoint",
                 *database as i32,
                 *dest as i32,

core/vdbe/insn.rs

@@ -1,9 +1,9 @@
 use std::num::NonZero;
 
 use super::{AggFunc, BranchOffset, CursorID, FuncCtx, PageIdx};
+use crate::storage::wal::CheckpointMode;
 use crate::types::{OwnedRecord, OwnedValue};
 use limbo_macros::Description;
-use crate::storage::wal::CheckpointMode;
 
 #[derive(Description, Debug)]
 pub enum Insn {
@@ -69,9 +69,9 @@ pub enum Insn {
     },
     // Checkpoint the database (applying wal file content to database file).
     Checkpoint {
-        database: usize, // checkpoint database P1
+        database: usize,                 // checkpoint database P1
         checkpoint_mode: CheckpointMode, // P2 checkpoint mode
-        dest: usize, // P3 checkpoint result
+        dest: usize,                     // P3 checkpoint result
     },
     // Divide lhs by rhs and place the remainder in dest register.
     Remainder {

core/vdbe/mod.rs

@@ -362,16 +362,24 @@ impl Program {
                     state.registers[*dest] = exec_bit_not(&state.registers[*reg]);
                     state.pc += 1;
                 }
-                Insn::Checkpoint { database: _, checkpoint_mode: _, dest } => {
-                    // Write 1 (checkpoint SQLITE_BUSY) or 0 (not busy).
-                    // fixme currently hard coded not implemented
-                    let result = self.connection
-                        .upgrade()
-                        .unwrap()
-                        .checkpoint();
+                Insn::Checkpoint {
+                    database: _,
+                    checkpoint_mode: _,
+                    dest,
+                } => {
+                    let result = self.connection.upgrade().unwrap().checkpoint();
                     match result {
-                        Ok(()) => state.registers[*dest] = OwnedValue::Integer(0),
-                        Err(err) => state.registers[*dest] = OwnedValue::Integer(1)
+                        Ok(()) => {
+                            // https://sqlite.org/pragma.html#pragma_wal_checkpoint
+                            // TODO make 2nd and 3rd cols available through checkpoint method
+                            // 1st col: 1 (checkpoint SQLITE_BUSY) or 0 (not busy).
+                            state.registers[*dest] = OwnedValue::Integer(0);
+                            // 2nd col: # modified pages written to wal file
+                            state.registers[*dest + 1] = OwnedValue::Integer(0);
+                            // 3rd col: # pages moved to db after checkpoint
+                            state.registers[*dest + 2] = OwnedValue::Integer(0);
+                        }
+                        Err(_err) => state.registers[*dest] = OwnedValue::Integer(1),
                     }
 
                     state.pc += 1;