Deliver libddprof_ffi as a shared library (#22)

* Deliver shared library alongside static library
* Add exporter example
* Activate LTO
* Optimize for size instead of speed
* Reduce number of codegen units to further reduce ouput library size.
* Make dynamic linking the default for libddprof_ffi.pc and provide libddprof_ffi-static.pc for static linking
* Remove RPATH/RUNPATH from cdylib on alpine-musl
Rust adds some weird RPATH/RUNPATH to cdylibs on alpine-musl (cf. https://git.alpinelinux.org/aports/tree/community/rust/alpine-target.patch,https://git.alpinelinux.org/aports/tree/community/rust/need-rpath.patch).

Cargo.toml

@@ -14,3 +14,6 @@ debug = 2 # full debug info
 
 [profile.release]
 debug = 1 # line tables only
+lto = true
+codegen-units = 1
+opt-level = "s" # optimize for size

LICENSE-3rdparty.yml

@@ -1,5 +1,5 @@
 ---
-root_name: "ddprof, ddprof-exporter, ddprof-ffi"
+root_name: "ddprof, ddprof-exporter, ddprof-profiles"
 third_party_libraries:
   - package_name: aho-corasick
     package_version: 0.7.18

ddprof-ffi/Cargo.toml

@@ -8,7 +8,9 @@ edition = "2018"
 license = "Apache-2.0"
 
 [lib]
-crate-type = ["lib", "staticlib"]
+# LTO is ignored if "lib" is added as crate type
+# cf. https://github.com/rust-lang/rust/issues/51009
+crate-type = ["staticlib", "cdylib"]
 
 [dependencies]
 chrono = "0.4"

ddprof/Cargo.toml

@@ -12,5 +12,4 @@ crate-type = ["cdylib", "lib"]
 
 [dependencies]
 ddprof-exporter = { path = "../ddprof-exporter" }
-ddprof-ffi = { path = "../ddprof-ffi" }
 ddprof-profiles = { path = "../ddprof-profiles" }

ddprof/src/lib.rs

@@ -2,5 +2,4 @@
 // This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2021-Present Datadog, Inc.
 
 pub use ddprof_exporter as exporter;
-pub use ddprof_ffi as ffi;
 pub use ddprof_profiles as profiles;

ddprof_ffi-static.pc.in

@@ -0,0 +1,17 @@
+# Unless explicitly stated otherwise all files in this repository are licensed
+# under the Apache License Version 2.0. This product includes software
+# developed at Datadog (https://www.datadoghq.com/). Copyright 2021-Present
+# Datadog, Inc.
+
+prefix=${pcfiledir}/../..
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib
+includedir=${prefix}/include
+
+Name: ddprof_ffi
+Description: Contains common code used to implement Datadog's Continuous Profilers.
+Version: @DDProf_FFI_VERSION@
+Requires:
+Libs: -L${libdir} ${libdir}/libddprof_ffi.a @DDProf_FFI_LIBRARIES@
+Libs.private:
+Cflags: -I${includedir}

ddprof_ffi.pc.in

@@ -12,6 +12,6 @@ Name: ddprof_ffi
 Description: Contains common code used to implement Datadog's Continuous Profilers.
 Version: @DDProf_FFI_VERSION@
 Requires:
-Libs: -L${libdir} -lddprof_ffi @DDProf_FFI_LIBRARIES@
+Libs: -L${libdir} -lddprof_ffi
 Libs.private:
 Cflags: -I${includedir}

examples/ffi/CMakeLists.txt

@@ -0,0 +1,9 @@
+project(ffi_examples)
+cmake_minimum_required(VERSION 3.19)
+
+find_package(DDProf)
+
+add_executable(exporter exporter.cpp)
+target_link_libraries(exporter DDProf::FFI)
+add_executable(profiles profiles.c)
+target_link_libraries(profiles DDProf::FFI)

examples/ffi/exporter.cpp

@@ -0,0 +1,150 @@
+extern "C"
+{
+#include <ddprof/ffi.h>
+}
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+static ddprof_ffi_ByteSlice to_byteslice(const char *s)
+{
+    return {.ptr = (uint8_t *)s,
+            .len = strlen(s)};
+}
+
+static ddprof_ffi_Slice_c_char to_slice_c_char(const char *s)
+{
+    return {.ptr = s,
+            .len = strlen(s)};
+}
+
+struct Deleter
+{
+    void operator()(ddprof_ffi_Profile *object)
+    {
+        ddprof_ffi_Profile_free(object);
+    }
+    void operator()(ddprof_ffi_ProfileExporterV3 *object)
+    {
+        ddprof_ffi_ProfileExporterV3_delete(object);
+    }
+    void operator()(ddprof_ffi_EncodedProfile *object)
+    {
+        ddprof_ffi_EncodedProfile_delete(object);
+    }
+};
+
+template <typename T>
+class Holder
+{
+public:
+    explicit Holder(T *object) : _object(object) {}
+    ~Holder() { Deleter{}(_object); }
+    Holder(const Holder &) = delete;
+    Holder &operator=(const Holder &) = delete;
+
+    operator T *() { return _object; }
+    T *operator->() { return _object; }
+
+    T *_object;
+};
+
+template <typename T>
+void print_error(const char *s, const T &err)
+{
+    printf("%s: (%.*s)\n", s, static_cast<int>(err.len), err.ptr);
+}
+
+int main(int argc, char* argv[])
+{
+    if (argc != 2) {
+        printf("Usage: exporter SERVICE_NAME\n");
+        return 1;
+    }
+    const char *api_key = getenv("DD_API_KEY");
+    if (!api_key) {
+        printf("DD_API_KEY environment variable is no set\n");
+        return 1;
+    }
+
+    const auto service = argv[1];
+
+    const ddprof_ffi_ValueType wall_time = {
+        .type_ = to_slice_c_char("wall-time"),
+        .unit = to_slice_c_char("nanoseconds"),
+    };
+
+    const ddprof_ffi_Slice_value_type sample_types = {&wall_time, 1};
+    const ddprof_ffi_Period period = {wall_time, 60};
+    Holder<ddprof_ffi_Profile> profile{ddprof_ffi_Profile_new(sample_types, &period)};
+
+    ddprof_ffi_Line root_line = {
+        .function = {
+            .name = to_slice_c_char("{main}"),
+            .filename = to_slice_c_char("/srv/example/index.php")},
+        .line = 0,
+    };
+
+    ddprof_ffi_Location root_location = {
+        // yes, a zero-initialized mapping is valid
+        .mapping = {},
+        .lines = {&root_line, 1},
+    };
+
+    int64_t value = 10;
+    const ddprof_ffi_Label label = {
+        .key = to_slice_c_char("language"),
+        .str = to_slice_c_char("php"),
+    };
+    ddprof_ffi_Sample sample = {
+        .locations = {&root_location, 1},
+        .values = {&value, 1},
+        .labels = {&label, 1},
+    };
+    ddprof_ffi_Profile_add(profile, sample);
+
+    Holder<ddprof_ffi_EncodedProfile> encoded_profile{ddprof_ffi_Profile_serialize(profile)};
+
+    ddprof_ffi_EndpointV3 endpoint = ddprof_ffi_EndpointV3_agentless(to_byteslice("datad0g.com"), to_byteslice(api_key));
+    ddprof_ffi_Tag tags[] = {{to_byteslice("service"), to_byteslice(service)}};
+    ddprof_ffi_NewProfileExporterV3Result exporter_new_result =
+        ddprof_ffi_ProfileExporterV3_new(
+            to_byteslice("native"), ddprof_ffi_Slice_tag{.ptr = tags, .len = sizeof(tags) / sizeof(tags[0])}, endpoint);
+
+    if (exporter_new_result.tag == DDPROF_FFI_NEW_PROFILE_EXPORTER_V3_RESULT_ERR)
+    {
+        print_error("Failed to create exporter: ", exporter_new_result.err);
+        return 1;
+    }
+
+    Holder<ddprof_ffi_ProfileExporterV3> exporter{exporter_new_result.ok};
+
+    ddprof_ffi_Buffer profile_buffer = {
+        .ptr = encoded_profile->buffer.ptr,
+        .len = encoded_profile->buffer.len,
+        .capacity = encoded_profile->buffer.capacity,
+    };
+
+    ddprof_ffi_File files_[] = {{
+        .name = to_byteslice("auto.pprof"),
+        .file = &profile_buffer,
+    }};
+
+    ddprof_ffi_Slice_file files = {
+        .ptr = files_, .len = sizeof files_ / sizeof *files_};
+
+    ddprof_ffi_Request *request = ddprof_ffi_ProfileExporterV3_build(
+        exporter, encoded_profile->start, encoded_profile->end, files, 10000);
+
+    ddprof_ffi_SendResult send_result = ddprof_ffi_ProfileExporterV3_send(exporter, request);
+    if (send_result.tag == DDPROF_FFI_SEND_RESULT_FAILURE)
+    {
+        print_error("Failed to send profile: ", send_result.failure);
+        return 1;
+    }
+    else
+    {
+        printf("Response code: %d\n", send_result.http_response.code);
+    }
+}

ffi-build.sh

@@ -12,6 +12,8 @@ mkdir -v -p "$destdir/include/ddprof" "$destdir/lib/pkgconfig" "$destdir/cmake"
 
 version=$(awk -F\" '$1 ~ /^version/ { print $2 }' < ddprof-ffi/Cargo.toml)
 target="$(rustc -vV | awk '/^host:/ { print $2 }')"
+shared_library_suffix=".so"
+remove_rpath=0
 
 # Rust provides this note about the link libraries:
 # note: Link against the following native artifacts when linking against this
@@ -26,10 +28,13 @@ case "$target" in
     "x86_64-alpine-linux-musl"|"aarch64-alpine-linux-musl")
         expected_native_static_libs=" -lssp_nonshared -lgcc_s -lc"
         native_static_libs=" -lssp_nonshared -lc"
+        # on alpine musl, Rust adds some weird runpath to cdylibs
+        remove_rpath=1
         ;;
     "x86_64-apple-darwin")
         expected_native_static_libs=" -framework Security -liconv -lSystem -lresolv -lc -lm -liconv"
         native_static_libs="${expected_native_static_libs}"
+        shared_library_suffix=".dylib"
         ;;
     "x86_64-unknown-linux-gnu"|"aarch64-unknown-linux-gnu")
         expected_native_static_libs=" -ldl -lrt -lpthread -lgcc_s -lc -lm -lrt -lpthread -lutil -ldl -lutil"
@@ -43,9 +48,12 @@ esac
 
 echo "Recognized platform '${target}'. Adding libs: ${native_static_libs}"
 sed < ddprof_ffi.pc.in "s/@DDProf_FFI_VERSION@/${version}/g" \
-    | sed "s/@DDProf_FFI_LIBRARIES@/${native_static_libs}/g" \
     > "$destdir/lib/pkgconfig/ddprof_ffi.pc"
 
+sed < ddprof_ffi-static.pc.in "s/@DDProf_FFI_VERSION@/${version}/g" \
+    | sed "s/@DDProf_FFI_LIBRARIES@/${native_static_libs}/g" \
+    > "$destdir/lib/pkgconfig/ddprof_ffi-static.pc"
+
 sed < cmake/DDProfConfig.cmake.in \
     > "$destdir/cmake/DDProfConfig.cmake" \
     "s/@DDProf_FFI_LIBRARIES@/${native_static_libs}/g"
@@ -54,9 +62,19 @@ cp -v LICENSE LICENSE-3rdparty.yml NOTICE "$destdir/"
 
 export RUSTFLAGS="${RUSTFLAGS:- -C relocation-model=pic}"
 
-echo "Building the libddprof_ffi.a library (may take some time)..."
+echo "Building the libddprof_ffi library (may take some time)..."
 cargo build --release --target "${target}"
-cp -v "target/${target}/release/libddprof_ffi.a" "$destdir/lib/"
+cp -v "target/${target}/release/libddprof_ffi.a" "target/${target}/release/libddprof_ffi${shared_library_suffix}" "$destdir/lib/"
+
+if [[ "$remove_rpath" -eq 1 ]]; then
+    patchelf --remove-rpath "$destdir/lib/libddprof_ffi${shared_library_suffix}"
+fi
+
+# objcopy might not be available on macOS
+if command -v objcopy > /dev/null; then
+    # Remove .llvmbc section which is not useful for clients
+    objcopy --remove-section .llvmbc "$destdir/lib/libddprof_ffi.a"
+fi
 
 echo "Checking that native-static-libs are as expected for this platform..."
 cd ddprof-ffi