Write first part of FFI library and header and use it in C app

Currently macOS only compilation

.gitignore

@@ -19,3 +19,4 @@ xcuserdata
 Cartfile.resolved
 Carthage
 glean-core/data
+glean_app

glean-core/ffi/examples/Makefile

@@ -0,0 +1,9 @@
+objects = glean_app.c ../../../target/debug/libglean_ffi.dylib
+headers = glean.h
+
+glean_app: $(objects) $(headers)
+	$(CC) $(CFLAGS) -o $@ $(objects)
+
+
+../../../target/debug/libglean_ffi.dylib: ../src/lib.rs
+	cargo build

glean-core/ffi/examples/glean.h

@@ -0,0 +1,23 @@
+#include <stdint.h>
+
+struct ExternError {
+  int32_t code;
+  char *message; // note: nullable
+};
+
+void glean_initialize();
+
+uint8_t glean_is_upload_enabled();
+
+uint64_t glean_new_boolean_metric(const char* name, const char* category, struct ExternError *err);
+
+uint64_t glean_new_counter_metric(const char* name, const char* category, struct ExternError *err);
+uint64_t glean_counter_add(uint64_t, uint32_t amount, struct ExternError *err);
+
+uint64_t glean_new_string_metric(const char* name, const char* category, struct ExternError *err);
+
+void glean_set_upload_enabled(uint8_t flag);
+
+char *glean_ping_collect(const char* ping_name, struct ExternError *error);
+
+void glean_str_free(char* ptr);

glean-core/ffi/examples/glean_app.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "glean.h"
+
+int main(void)
+{
+  glean_initialize();
+
+  printf("Glean upload enabled? %d\n", glean_is_upload_enabled());
+  glean_set_upload_enabled(0);
+  printf("Glean upload enabled? %d\n", glean_is_upload_enabled());
+  glean_set_upload_enabled(1);
+
+  struct ExternError err;
+  uint64_t metric = glean_new_counter_metric("counter", "local", &err);
+  printf("Created counter: %llu\n", metric);
+
+  glean_counter_add(metric, 2, &err);
+
+  char *payload = glean_ping_collect("core", &err);
+  printf("Payload:\n%s\n", payload);
+  glean_str_free(payload);
+
+  return 0;
+}

glean-core/ffi/src/lib.rs

@@ -1,37 +1,96 @@
+use std::os::raw::c_char;
+
 use lazy_static::lazy_static;
 use ffi_support::{
+    IntoFfi,
     FfiStr,
     ConcurrentHandleMap,
     ExternError,
     define_handle_map_deleter,
     define_string_destructor,
+    call_with_output,
 };
 
 use glean_core::{
     Glean,
     CommonMetricData,
-    metrics::BooleanMetric,
+    metrics::*,
 };
 
 lazy_static! {
     static ref BOOLEAN_METRICS: ConcurrentHandleMap<BooleanMetric> = ConcurrentHandleMap::new();
+    static ref STRING_METRICS: ConcurrentHandleMap<StringMetric> = ConcurrentHandleMap::new();
+    static ref COUNTER_METRICS: ConcurrentHandleMap<CounterMetric> = ConcurrentHandleMap::new();
 }
 
 #[no_mangle]
 pub extern fn glean_initialize() {
-    Glean::initialize();
+    Glean::singleton().initialize();
 }
 
 #[no_mangle]
-pub extern fn glean_new_boolean_metric(name: FfiStr<'_>, category: FfiStr<'_>, err: &mut ExternError) -> u64 {
+pub extern fn glean_is_upload_enabled() -> u8 {
+    Glean::singleton().is_upload_enabled().into_ffi_value()
+}
+
+#[no_mangle]
+pub extern fn glean_set_upload_enabled(flag: u8) {
+    let flag = flag != 0;
+    Glean::singleton().set_upload_enabled(flag);
+}
+
+#[no_mangle]
+pub extern fn glean_new_boolean_metric(name: FfiStr, category: FfiStr, err: &mut ExternError) -> u64 {
     BOOLEAN_METRICS.insert_with_output(err, || {
         BooleanMetric::new(CommonMetricData {
             name: name.into_string(),
             category: category.into_string(),
+            send_in_pings: vec!["core".into()],
             .. Default::default()
         })
     })
 }
 
+#[no_mangle]
+pub extern fn glean_new_string_metric(name: FfiStr, category: FfiStr, err: &mut ExternError) -> u64 {
+    STRING_METRICS.insert_with_output(err, || {
+        StringMetric::new(CommonMetricData {
+            name: name.into_string(),
+            category: category.into_string(),
+            send_in_pings: vec!["core".into()],
+            .. Default::default()
+        })
+    })
+}
+
+#[no_mangle]
+pub extern fn glean_new_counter_metric(name: FfiStr, category: FfiStr, err: &mut ExternError) -> u64 {
+    COUNTER_METRICS.insert_with_output(err, || {
+        CounterMetric::new(CommonMetricData {
+            name: name.into_string(),
+            category: category.into_string(),
+            send_in_pings: vec!["core".into()],
+            .. Default::default()
+        })
+    })
+}
+
+#[no_mangle]
+pub extern fn glean_counter_add(metric_id: u64, amount: u32, error: &mut ExternError) {
+    COUNTER_METRICS.call_with_output(error, metric_id, |metric| {
+        metric.add(amount);
+        ()
+    })
+}
+
+#[no_mangle]
+pub extern fn glean_ping_collect(ping_name: FfiStr, error: &mut ExternError) -> *mut c_char {
+    call_with_output(error, || {
+        let ping_maker = glean_core::ping::PingMaker::new();
+        let ping = ping_maker.collect_string(ping_name.as_str());
+        ping
+    })
+}
+
 define_handle_map_deleter!(BOOLEAN_METRICS, glean_destroy_boolean_metric);
 define_string_destructor!(glean_str_free);