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atrace_hal.cc22-Oct-20202K
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health_hal.cc22-Oct-20202.5K
health_hal.h22-Oct-20201.4K
incident_service.cc22-Oct-20202K
incident_service.h22-Oct-20201.3K
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README.md22-Oct-20201.7K

README.md

      1 This directory contains code that accesses Android (hw)binder interfaces and is
      2 dynamically loaded and used by traced_probes / perfetto command line client.
      3 The code in this directory is built as a separate .so library and can depend on
      4 on Android internals.
      5 
      6 Block diagram:
      7 
      8 ```
      9 +---------------+       +---------------------------------+
     10 | traced_probes |- - -> | libperfetto_android_internal.so |
     11 +---------------+  ^    +---------------+-----------------+
     12                    |                    |
     13                    |                    | [  Non-NDK libraries ]
     14                    |                    +-> libbase.so
     15                    |                    +-> libutils.so
     16                    |                    +-> libhidltransport.so
     17                    |                    +-> libhwbinder.so
     18                    |                    +-> android.hardware.xxx (a] 2.0
     19                    |
     20                    + dynamically loaded on first use via dlopen()
     21 ```
     22 
     23 The major reason for using a separate .so() and introducing the shared library
     24 layer is avoiding the cost of linker relocations (~150 KB private dirty)
     25 required for loading the graph of binder-related libraries.
     26 
     27 The general structure and rules for code in this directory is as-follows:
     28 - Targets herein defined must be leaf targets. Dependencies to perfetto targets
     29   (e.g. base) are not allowed, as doing that would create ODR violations.
     30 - Headers (e.g. health_hal.h) must have a plain old C interface (to avoid
     31   dealing with name mangling) and should not expose neither android internal
     32   structure/types nor struct/types defined in perfetto headers outside of this
     33   directory.
     34 - Dependencies to Android internal headers are allowed only in .cc files, not
     35   in headers.
     36