add tc_task_get_taskmap

lib/src/kv.rs

@@ -0,0 +1,103 @@
+use crate::traits::*;
+use crate::types::*;
+
+/// TCKV contains a key/value pair that is part of a task.
+///
+/// Neither key nor value are ever NULL.  They remain owned by the TCKV and
+/// will be freed when it is freed with tc_kv_list_free.
+#[repr(C)]
+pub struct TCKV {
+    pub key: *mut TCString<'static>,
+    pub value: *mut TCString<'static>,
+}
+
+impl PassByValue for TCKV {
+    type RustType = (TCString<'static>, TCString<'static>);
+
+    unsafe fn from_ctype(self) -> Self::RustType {
+        // SAFETY:
+        //  - self is owned, so we can take ownership of this TCString
+        //  - self.key is a valid, non-null TCString (see type docstring)
+        let key = unsafe { TCString::take_from_arg(self.key) };
+        // SAFETY: (same)
+        let value = unsafe { TCString::take_from_arg(self.value) };
+        (key, value)
+    }
+
+    fn as_ctype((key, value): Self::RustType) -> Self {
+        TCKV {
+            // SAFETY: caller assumes ownership of this value
+            key: unsafe { key.return_val() },
+            // SAFETY: caller assumes ownership of this value
+            value: unsafe { value.return_val() },
+        }
+    }
+}
+
+/// TCKVList represents a list of key/value pairs.
+///
+/// The content of this struct must be treated as read-only.
+#[repr(C)]
+pub struct TCKVList {
+    /// number of key/value pairs in items
+    len: libc::size_t,
+
+    /// total size of items (internal use only)
+    _capacity: libc::size_t,
+
+    /// array of TCKV's. these remain owned by the TCKVList instance and will be freed by
+    /// tc_kv_list_free.  This pointer is never NULL for a valid TCKVList.
+    items: *const TCKV,
+}
+
+impl CList for TCKVList {
+    type Element = TCKV;
+
+    unsafe fn from_raw_parts(items: *const Self::Element, len: usize, cap: usize) -> Self {
+        TCKVList {
+            len,
+            _capacity: cap,
+            items,
+        }
+    }
+
+    fn into_raw_parts(self) -> (*const Self::Element, usize, usize) {
+        (self.items, self.len, self._capacity)
+    }
+}
+
+/// Free a TCKVList instance.  The instance, and all TCKVs it contains, must not be used after
+/// this call.
+///
+/// When this call returns, the `items` pointer will be NULL, signalling an invalid TCKVList.
+#[no_mangle]
+pub unsafe extern "C" fn tc_kv_list_free(tckvs: *mut TCKVList) {
+    // SAFETY:
+    //  - tckvs is not NULL and points to a valid TCKVList (caller is not allowed to
+    //    modify the list)
+    //  - caller promises not to use the value after return
+    unsafe { drop_value_list(tckvs) }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn empty_list_has_non_null_pointer() {
+        let tckvs = TCKVList::return_val(Vec::new());
+        assert!(!tckvs.items.is_null());
+        assert_eq!(tckvs.len, 0);
+        assert_eq!(tckvs._capacity, 0);
+    }
+
+    #[test]
+    fn free_sets_null_pointer() {
+        let mut tckvs = TCKVList::return_val(Vec::new());
+        // SAFETY: testing expected behavior
+        unsafe { tc_kv_list_free(&mut tckvs) };
+        assert!(tckvs.items.is_null());
+        assert_eq!(tckvs.len, 0);
+        assert_eq!(tckvs._capacity, 0);
+    }
+}

lib/src/lib.rs

@@ -7,6 +7,7 @@ mod util;
 
 pub mod annotation;
 pub mod atomic;
+pub mod kv;
 pub mod replica;
 pub mod result;
 pub mod status;
@@ -18,6 +19,7 @@ pub mod workingset;
 
 pub(crate) mod types {
     pub(crate) use crate::annotation::{TCAnnotation, TCAnnotationList};
+    pub(crate) use crate::kv::{TCKVList, TCKV};
     pub(crate) use crate::replica::TCReplica;
     pub(crate) use crate::result::TCResult;
     pub(crate) use crate::status::TCStatus;

lib/src/task.rs

@@ -243,7 +243,24 @@ pub unsafe extern "C" fn tc_task_get_status<'a>(task: *mut TCTask) -> TCStatus {
     wrap(task, |task| task.get_status().into())
 }
 
-// TODO: tc_task_get_taskmap (?? then we have to wrap a map..)
+/// Get the underlying key/value pairs for this task.  The returned TCKVList is
+/// a "snapshot" of the task and will not be updated if the task is subsequently
+/// modified.
+#[no_mangle]
+pub unsafe extern "C" fn tc_task_get_taskmap(task: *mut TCTask) -> TCKVList {
+    wrap(task, |task| {
+        let vec: Vec<TCKV> = task
+            .get_taskmap()
+            .iter()
+            .map(|(k, v)| {
+                let key = TCString::from(k.as_ref());
+                let value = TCString::from(v.as_ref());
+                TCKV::as_ctype((key, value))
+            })
+            .collect();
+        TCKVList::return_val(vec)
+    })
+}
 
 /// Get a task's description, or NULL if the task cannot be represented as a C string (e.g., if it
 /// contains embedded NUL characters).