There are three options to use this library:
In this mode Producer, Consumers and the Service are hosted in the same process. This is not too interesting other than tests and particular cases of nesting tracing instances coming from different libraries within the same process (concrete example v8, skia and webrtc in Chrome). In this configuration, the client is expected to at least:
core/tracing_service.h
)core/producer.h
) and connect it to the service.test/test_task_runner.h
)core/shared_memory.h
) which is simply backed by a malloc() buffer.The include/unix_rpc
provides the building blocks necessary to implement a RPC mechanism that allows Producer(s), Consumer(s) and Service to be hosted on different processes on the same machine and talk over a UNIX domain socket.
UnixServiceConnection::ConnectAsProducer()
.Service
must be instantiated via UnixServiceHost::CreateInstance()
. The returned instance encapsulates the Service
and exposes two UNIX sockets (one for Producer(s), one for Consumer(s)) on the current process.Similar to Option 2, but the client creates its own transport mechanism, defining how methods are proxies between instances and providing a SharedMemory implementation that can be transferred through RPC. Concrete example of this is Chrome implementing this library over a Mojo transport.
include/
Is the public API that clients of this library are allowed to depend on. Headers inside include/ cannot depend on anything else.
src/
Is the actual implementation that clients can link but not expected to access at a source-code level.
Both have the following sub-structure:
{include,src}/core/
“Core” is the pure c++11 tracing machinery that deals with bookkeeping, ring-buffering, partitioning and multiplexing but knows nothing about platform-specific things like implementation of shared memory and RPC mechanism.
{include,src}/unix_rpc/
A concrete implementation of the transport layer based on unix domain sockets and posix shared memory.