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Commit f3a7988e authored by Vic Yang's avatar Vic Yang
Browse files

liblp: Make kDefaultGroup a string_view 

Changing the type of kDefaultGroup from std::string to std::string_view
allows us to make it a constexpr object.  Since kDefaultGroup is the
only dirty object in liblp .bss at runtime, this change turns the .bss
page clean and thus saves 4KB per library load.

Bug: 138856262
Test: Boot cuttlefish and check liblp bss is clean for all 5 processes
      that are using it.
Change-Id: I7d7c0992e0ab769f070807f24e1275ffed424b5b
parent 23a87716

fs_mgr/liblp/builder.cpp

+4 −3
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <string.h>



#include <algorithm>

#include <string_view>



#include <android-base/properties.h>

#include <android-base/unique_fd.h>
@@ -33,7 +34,7 @@ namespace fs_mgr { 
std::optional<bool> MetadataBuilder::sABOverride;

std::optional<bool> MetadataBuilder::sRetrofitDap;



static const std::string kDefaultGroup = "default";

static constexpr std::string_view kDefaultGroup = "default";



bool LinearExtent::AddTo(LpMetadata* out) const {

    if (device_index_ >= out->block_devices.size()) {
@@ -414,7 +415,7 @@ bool MetadataBuilder::Init(const std::vector<BlockDeviceInfo>& block_devices, 
    geometry_.metadata_slot_count = metadata_slot_count;

    geometry_.logical_block_size = logical_block_size;



    if (!AddGroup(kDefaultGroup, 0)) {

    if (!AddGroup(std::string(kDefaultGroup), 0)) {

        return false;

    }

    return true;
@@ -430,7 +431,7 @@ bool MetadataBuilder::AddGroup(const std::string& group_name, uint64_t maximum_s 
}



Partition* MetadataBuilder::AddPartition(const std::string& name, uint32_t attributes) {

    return AddPartition(name, kDefaultGroup, attributes);

    return AddPartition(name, std::string(kDefaultGroup), attributes);

}



Partition* MetadataBuilder::AddPartition(const std::string& name, const std::string& group_name,