gs-common/modem: clock manager interface

A lot of modem code requires sleeping while vendor services do some
background processing. Since we don't want to actually sleep for unit
tests, an interface is provided here so that a fake sleep can be
injected.

Test: N/A. Directly forwards methods or does nothing.
Bug: 302435001
Change-Id: I3bcf0307156d93756d69cd9f749c88b508ba9466

modem/clock_manager/Android.bp

@@ -0,0 +1,9 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_library {
+    name: "modem_clock_manager",
+    export_include_dirs: [ "include" ],
+    vendor_available: true,
+}

modem/clock_manager/fake/Android.bp

@@ -0,0 +1,15 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+cc_defaults {
+    name: "fake_modem_clock_manager_defaults",
+    shared_libs: [ "modem_clock_manager" ],
+}
+
+cc_library_static {
+    name: "fake_modem_clock_manager",
+    export_include_dirs: [ "include" ],
+    defaults: [ "fake_modem_clock_manager_defaults" ],
+    vendor_available: true,
+}

modem/clock_manager/fake/include/fake_clock_manager.h

@@ -0,0 +1,21 @@
+#include "clock_manager.h"
+
+namespace pixel_modem {
+
+/**
+ * @brief Fake implementation of clock manager that doesn't actually sleep.
+ *
+ * A lot of vendor code don't have return values and instead force the client
+ * codes to sleep for a specified period of time before checking some system
+ * properties. However, since unit tests don't rely on the real vendor
+ * implementations, these sleeps should be ignored and so a fake clock should be
+ * used.
+ *
+ * Since this definition is unlikely to change, it will be defined in the header
+ * and not an implementation file.
+ */
+struct FakeClockManager : public ClockManager {
+  void Sleep(size_t /*seconds*/) const override{};
+};
+
+}  // namespace pixel_modem

modem/clock_manager/impl/Android.bp

@@ -0,0 +1,16 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+modem_clock_manager_impl_public_deps = [
+    "modem_clock_manager",
+]
+
+cc_library {
+    name: "modem_clock_manager_impl",
+    export_include_dirs: [ "include" ],
+    srcs: [ "clock_manager_impl.cpp" ],
+    shared_libs: modem_clock_manager_impl_public_deps,
+    export_shared_lib_headers: modem_clock_manager_impl_public_deps,
+    vendor_available: true,
+}

modem/clock_manager/impl/clock_manager_impl.cpp

@@ -0,0 +1,9 @@
+#include "clock_manager_impl.h"
+
+#include <unistd.h>
+
+namespace pixel_modem {
+
+void ClockManagerImpl::Sleep(size_t seconds) const { sleep(seconds); }
+
+}  // namespace pixel_modem

modem/clock_manager/impl/include/clock_manager_impl.h

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <cstddef>
+
+#include "clock_manager.h"
+
+namespace pixel_modem {
+
+struct ClockManagerImpl : public ClockManager {
+  void Sleep(size_t seconds) const override;
+};
+
+}  // namespace pixel_modem

modem/clock_manager/include/clock_manager.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <cstddef>
+
+namespace pixel_modem {
+
+/**
+ * @brief Interface for time based operations.
+ *
+ * This interface was intentionally not called `Clock`, like the Java side
+ * counterpart since it's likely that clients would call the local variable
+ * `clock(_)`, which would clash with the C defined `clock` method.
+ */
+struct ClockManager {
+  virtual ~ClockManager() = default;
+
+  /**
+   * @brief Sleep the thread for a given number of seconds.
+   *
+   * @param seconds Minimum number of seconds to sleep for. Note, this is
+   * different than the Java android clock which accepts seconds. This was done
+   * because C++ developers are likely more familiar with the `sleep` command,
+   * which accepts seconds.
+   */
+  virtual void Sleep(size_t seconds) const = 0;
+};
+
+}  // namespace pixel_modem