Implement missing CRUD functionality (#13)

* fix,feat: Implement column name based filtering for the scan functions since we run into problems with delete and update if we don't. Implement insertion and deletion

* feat: Implement the update functionality. All CRUD functions are now done

Author: if-loop69420

src/lib.rs

@@ -1,11 +1,8 @@
-use etcd_client::{Client, GetOptions, KeyValue};
-use futures::Stream;
+use etcd_client::{Client, DeleteOptions, GetOptions, KeyValue, PutOptions};
 use pgrx::pg_sys::panic::ErrorReport;
-use pgrx::pg_sys::ErrorContextCallback;
 use pgrx::PgSqlErrorCode;
 use supabase_wrappers::prelude::*;
 use thiserror::Error;
-use tokio::runtime::*;
 
 pgrx::pg_module_magic!();
 
@@ -19,23 +16,37 @@ pub(crate) struct EtcdFdw {
     rt: Runtime,
     prefix: String,
     fetch_results: Vec<KeyValue>,
+    fetch_key: bool,
+    fetch_value: bool,
 }
 
 #[derive(Error, Debug)]
 pub enum EtcdFdwError {
-    #[error("Failed to fetch from etcd")]
+    #[error("Failed to fetch from etcd: {0}")]
     FetchError(String),
 
-    #[error("Failed to connect to client")]
+    #[error("Failed to send update to etcd: {0}")]
+    UpdateError(String),
+
+    #[error("Failed to connect to client: {0}")]
     ClientConnectionError(String),
 
     #[error("No connection string option was specified. Specify it with connstr")]
     NoConnStr(()),
+
+    #[error("Column {0} is not contained in the input dataset")]
+    MissingColumn(String),
+
+    #[error("Key {0} already exists in etcd. No duplicates allowed")]
+    KeyAlreadyExists(String),
+
+    #[error("Key {0} doesn't exist in etcd")]
+    KeyDoesntExist(String),
 }
 
 impl From<EtcdFdwError> for ErrorReport {
-    fn from(_value: EtcdFdwError) -> Self {
-        ErrorReport::new(PgSqlErrorCode::ERRCODE_FDW_ERROR, "", "")
+    fn from(value: EtcdFdwError) -> Self {
+        ErrorReport::new(PgSqlErrorCode::ERRCODE_FDW_ERROR, format!("{}", value), "")
     }
 }
 
@@ -44,7 +55,7 @@ type EtcdFdwResult<T> = std::result::Result<T, EtcdFdwError>;
 impl ForeignDataWrapper<EtcdFdwError> for EtcdFdw {
     fn new(server: ForeignServer) -> EtcdFdwResult<EtcdFdw> {
         // Open connection to etcd specified through the server parameter
-        let rt = tokio::runtime::Runtime::new().unwrap();
+        let rt = tokio::runtime::Runtime::new().expect("Tokio runtime should be initialized");
 
         // Add parsing for the multi host connection string things here
         let server_name = match server.options.get("connstr") {
@@ -67,13 +78,15 @@ impl ForeignDataWrapper<EtcdFdwError> for EtcdFdw {
             rt,
             prefix,
             fetch_results,
+            fetch_key: false,
+            fetch_value: false,
         })
     }
 
     fn begin_scan(
         &mut self,
         _quals: &[Qual],
-        _columns: &[Column],
+        columns: &[Column],
         _sorts: &[Sort],
         limit: &Option<Limit>,
         _options: &std::collections::HashMap<String, String>,
@@ -85,7 +98,10 @@ impl ForeignDataWrapper<EtcdFdwError> for EtcdFdw {
             Some(x) => get_options = get_options.with_limit(x.count),
             None => (),
         }
-        // Also do quals, columns and sorts.
+        // Check if columns contains key and value
+        let colnames: Vec<String> = columns.iter().map(|x| x.name.clone()).collect();
+        self.fetch_key = colnames.contains(&String::from("key"));
+        self.fetch_value = colnames.contains(&String::from("value"));
 
         let result = self
             .rt
@@ -110,34 +126,141 @@ impl ForeignDataWrapper<EtcdFdwError> for EtcdFdw {
                 let value = x
                     .value_str()
                     .expect("Expected a value, but the value was empty");
-                row.push("key", Some(Cell::String(key.to_string())));
-                row.push("value", Some(Cell::String(value.to_string())));
+                if self.fetch_key {
+                    row.push("key", Some(Cell::String(key.to_string())));
+                }
+                if self.fetch_value {
+                    row.push("value", Some(Cell::String(value.to_string())));
+                }
             }))
         }
     }
 
     fn end_scan(&mut self) -> EtcdFdwResult<()> {
         self.fetch_results = vec![];
+        self.fetch_key = false;
+        self.fetch_value = false;
         Ok(())
     }
 
     fn begin_modify(
         &mut self,
         _options: &std::collections::HashMap<String, String>,
     ) -> Result<(), EtcdFdwError> {
-        todo!("Begin modify is not yet implemented")
+        // This currently does nothing
+        Ok(())
     }
 
-    fn insert(&mut self, _row: &Row) -> Result<(), EtcdFdwError> {
-        todo!("Insert is not yet implemented")
+    fn insert(&mut self, row: &Row) -> Result<(), EtcdFdwError> {
+        let key_string = match row
+            .cols
+            .iter()
+            .zip(row.cells.clone())
+            .filter(|(name, _cell)| *name == "key")
+            .last()
+        {
+            Some(x) => x.1.expect("The key column should be present").to_string(),
+            None => return Err(EtcdFdwError::MissingColumn("key".to_string())),
+        };
+        let value_string = match row
+            .cols
+            .iter()
+            .zip(row.cells.clone())
+            .filter(|(name, _cell)| *name == "value")
+            .last()
+        {
+            Some(x) => x.1.expect("The value column should be present").to_string(),
+            None => return Err(EtcdFdwError::MissingColumn("value".to_string())),
+        };
+        let key = key_string.trim_matches(|x| x == '\'');
+        let value = value_string.trim_matches(|x| x == '\'');
+
+        // See if key already exists. Error if it does
+        match self.rt.block_on(self.client.get(key, None)) {
+            Ok(x) => {
+                if let Some(y) = x.kvs().first() {
+                    if y.key_str().expect("There should be a key string") == key {
+                        return Err(EtcdFdwError::KeyAlreadyExists(format!("{}", key)));
+                    }
+                }
+            }
+            Err(e) => return Err(EtcdFdwError::FetchError(e.to_string())),
+        }
+
+        match self
+            .rt
+            .block_on(self.client.put(key, value, Some(PutOptions::new())))
+        {
+            Ok(_) => Ok(()),
+            Err(e) => return Err(EtcdFdwError::UpdateError(e.to_string())),
+        }
     }
 
-    fn update(&mut self, _rowid: &Cell, _new_row: &Row) -> Result<(), EtcdFdwError> {
-        todo!("Update is not yet implemented")
+    fn update(&mut self, rowid: &Cell, new_row: &Row) -> Result<(), EtcdFdwError> {
+        let key_string = rowid.to_string();
+        let key = key_string.trim_matches(|x| x == '\'');
+
+        match self.rt.block_on(self.client.get(key, None)) {
+            Ok(x) => {
+                if let Some(y) = x.kvs().first() {
+                    if y.key_str().expect("There should be a key string") != key {
+                        return Err(EtcdFdwError::KeyDoesntExist(format!("{}", key)));
+                    }
+                }
+            }
+            Err(e) => return Err(EtcdFdwError::FetchError(e.to_string())),
+        }
+
+        let value_string = match new_row
+            .cols
+            .iter()
+            .zip(new_row.cells.clone())
+            .filter(|(name, _cell)| *name == "value")
+            .last()
+        {
+            Some(x) => x.1.expect("The value column should be present").to_string(),
+            None => return Err(EtcdFdwError::MissingColumn("value".to_string())),
+        };
+        let value = value_string.trim_matches(|x| x == '\'');
+
+        match self.rt.block_on(self.client.put(key, value, None)) {
+            Ok(_) => Ok(()),
+            Err(e) => return Err(EtcdFdwError::UpdateError(e.to_string())),
+        }
     }
 
-    fn delete(&mut self, _rowid: &Cell) -> Result<(), EtcdFdwError> {
-        todo!("Delete is not yet implemented")
+    fn delete(&mut self, rowid: &Cell) -> Result<(), EtcdFdwError> {
+        let key_string = rowid.to_string();
+        let key = key_string.trim_matches(|x| x == '\'');
+
+        let delete_options = DeleteOptions::new();
+
+        match self.rt.block_on(self.client.get(key, None)) {
+            Ok(x) => {
+                if let Some(y) = x.kvs().first() {
+                    if y.key_str().expect("There should be a key string") != key {
+                        return Err(EtcdFdwError::KeyDoesntExist(format!("{}", key)));
+                    }
+                }
+            }
+            Err(e) => return Err(EtcdFdwError::FetchError(e.to_string())),
+        }
+
+        match self
+            .rt
+            .block_on(self.client.delete(key, Some(delete_options)))
+        {
+            Ok(x) => {
+                if x.deleted() == 0 {
+                    return Err(EtcdFdwError::UpdateError(format!(
+                        "Deletion seemingly successful, but deleted count is {}",
+                        x.deleted()
+                    )));
+                }
+                Ok(())
+            }
+            Err(e) => Err(EtcdFdwError::UpdateError(e.to_string())),
+        }
     }
 
     // fn get_rel_size(
@@ -152,6 +275,7 @@ impl ForeignDataWrapper<EtcdFdwError> for EtcdFdw {
     // }
 
     fn end_modify(&mut self) -> Result<(), EtcdFdwError> {
-        todo!()
+        // This currently also does nothing
+        Ok(())
     }
 }