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pack: Add support for using a common pack dir for multiple traces #3735

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merged 1 commit into from
Sep 20, 2024
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pack: Add support for using a common pack dir for multiple traces #3735

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2 changes: 1 addition & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ endif()
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${FLAGS_COMMON} -Wstrict-prototypes -std=gnu11")
# Define __STDC_LIMIT_MACROS so |#include <stdint.h>| works as expected.
# Define __STDC_FORMAT_MACROS so |#include <inttypes.h>| works as expected.
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAGS_COMMON} -D__STDC_LIMIT_MACROS -D__STDC_FORMAT_MACROS -std=c++14")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAGS_COMMON} -D__STDC_LIMIT_MACROS -D__STDC_FORMAT_MACROS -std=c++17")

# We support three build types:
# DEBUG: suitable for debugging rr
Expand Down
34 changes: 31 additions & 3 deletions src/PackCommand.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include <unistd.h>

#include <algorithm>
#include <filesystem>
#include <limits>
#include <map>
#include <set>
Expand Down Expand Up @@ -67,6 +68,7 @@ struct PackFlags {
/* If true, insert symlinks into the trace dir which point to the original
* files, rather than copying the files themselves */
bool symlink;
std::string pack_dir;

PackFlags()
: symlink(false) {}
Expand Down Expand Up @@ -99,6 +101,12 @@ bool operator<(const FsExtentsHash& h1, const FsExtentsHash& h2) {
return memcmp(h1.bytes, h2.bytes, sizeof(h1)) < 0;
}

struct PackDir {
string dir;
map<FileHash, string> mapped_files;
PackDir(string dir) : dir(dir) {}
};

static bool name_comparator(const TraceReader::MappedData& d1,
const TraceReader::MappedData d2) {
return d1.file_name < d2.file_name;
Expand Down Expand Up @@ -528,7 +536,8 @@ static map<string, string> compute_canonical_symlink_map(
* for all files with that hash.
*/
static map<string, string> compute_canonical_mmapped_files(
const string& trace_dir) {
const string& trace_dir,
PackDir &pack_dir) {
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& before the space please

map<string, FileHash> file_info = gather_file_info(trace_dir);

map<FileHash, string> hash_to_name;
Expand All @@ -545,10 +554,24 @@ static map<string, string> compute_canonical_mmapped_files(

int name_index = 0;
for (auto& p : hash_to_name) {
// Check if this in our common pack directory
auto it = pack_dir.mapped_files.find(p.first);
if (it != pack_dir.mapped_files.end()) {
LOG(debug) << "Found in common pack dir";
p.second = symlink_into_trace(filesystem::relative(it->second, trace_dir), trace_dir, &name_index);
continue;
}

// Copy hardlinked files into the trace to avoid the possibility of someone
// overwriting the original file.
if (is_hardlink(p.second) || !is_in_trace_dir(p.second, trace_dir)) {
p.second = copy_into_trace(p.second, trace_dir, &name_index);
if (pack_dir.dir != "") {
// If a pack dir is specified, first copy into pack dir, then symlink into trace.
auto path = pack_dir.mapped_files[p.first] = copy_into_trace(p.second, pack_dir.dir, &name_index);
p.second = symlink_into_trace(filesystem::relative(path, trace_dir), trace_dir, &name_index);
} else {
p.second = copy_into_trace(p.second, trace_dir, &name_index);
}
}
}

Expand Down Expand Up @@ -656,6 +679,7 @@ static int pack(const string& trace_dir, const PackFlags& flags) {
dir = reader.dir();
}

PackDir pack_dir(flags.pack_dir);
char buf[PATH_MAX];
char* ret = realpath(dir.c_str(), buf);
if (!ret) {
Expand All @@ -670,7 +694,7 @@ static int pack(const string& trace_dir, const PackFlags& flags) {
delete_unnecessary_files(canonical_symlink_map, abspath);
} else {
map<string, string> canonical_mmapped_files =
compute_canonical_mmapped_files(abspath);
compute_canonical_mmapped_files(abspath, pack_dir);
rewrite_mmaps(canonical_mmapped_files, abspath);
delete_unnecessary_files(canonical_mmapped_files, abspath);
}
Expand All @@ -685,6 +709,7 @@ static int pack(const string& trace_dir, const PackFlags& flags) {
static bool parse_pack_arg(vector<string>& args, PackFlags& flags) {
static const OptionSpec options[] = {
{ 0, "symlink", NO_PARAMETER },
{ 1, "pack-dir", HAS_PARAMETER },
};
ParsedOption opt;
auto args_copy = args;
Expand All @@ -696,6 +721,9 @@ static bool parse_pack_arg(vector<string>& args, PackFlags& flags) {
case 0:
flags.symlink = true;
break;
case 1:
flags.pack_dir = opt.value;
break;
default:
DEBUG_ASSERT(0 && "Unknown pack option");
}
Expand Down
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