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Truncate long Uprobe name and append hash #9

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Truncate long Uprobe name and append hash #9

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bea0fc8
Revert "Fix random_alnum_string in BPF.cc."
chengruizhe Jan 18, 2023
424de3f
Revert "Shorten a name that is too long for attaching uprobe"
chengruizhe Jan 18, 2023
e554558
truncate long uprobe name and append hash
chengruizhe Jan 18, 2023
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33 changes: 9 additions & 24 deletions src/cc/api/BPF.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,6 @@
#include <fcntl.h>
#include <iostream>
#include <memory>
#include <random>
#include <sstream>
#include <sys/stat.h>
#include <sys/types.h>
Expand Down Expand Up @@ -856,31 +855,23 @@ bool BPF::add_module(std::string module)

namespace {

std::string random_alnum_string(const int len) {
static constexpr char kDict[] = "0123456789abcdefghijklmnopqrstuvwxyz";
static std::mt19937 gen;
static std::uniform_int_distribution<size_t> dist(0, sizeof(kDict) - 2);
std::string res;
res.resize(len);
for (int i = 0; i < len; ++i) {
res[i] = kDict[dist(gen)];
}
return res;
}

constexpr size_t kEventNameSizeLimit = 224;

std::string shorten_event_name(const std::string& name) {
constexpr size_t kRandomSuffixLen = 16;
constexpr size_t kHashSuffixLen = 16;
std::string res;
res.reserve(kEventNameSizeLimit);
res.assign(name);
res.resize(kEventNameSizeLimit - kRandomSuffixLen);
res.append(random_alnum_string(kRandomSuffixLen));
res.resize(kEventNameSizeLimit - kHashSuffixLen);

std::stringstream stream;
size_t hash = std::hash<std::string>{}(name);
stream << std::hex << hash;
res.append(stream.str());
return res;
}

} // namespace
} // namespace

std::string BPF::get_uprobe_event(const std::string& binary_path,
uint64_t offset, bpf_probe_attach_type type,
Expand All @@ -891,13 +882,7 @@ std::string BPF::get_uprobe_event(const std::string& binary_path,
if (pid != -1)
res += "_" + std::to_string(pid);
if (res.size() > kEventNameSizeLimit) {
auto iter = name_map_.find(res);
if (iter != name_map_.end()) {
return iter->second;
}
std::string shortend_name = shorten_event_name(res);
name_map_[res] = shortend_name;
return shortend_name;
return shorten_event_name(res);
}
return res;
}
Expand Down
3 changes: 0 additions & 3 deletions src/cc/api/BPF.h
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Original file line number Diff line number Diff line change
Expand Up @@ -341,9 +341,6 @@ class BPF {
std::string all_bpf_program_;

std::map<std::string, open_probe_t> kprobes_;
// For uprobes, if the binary path is longer than 250, we'll shorten them. And then keep the
// mapping.
std::map<std::string, std::string> name_map_;
std::map<std::string, open_probe_t> uprobes_;
std::map<std::string, open_probe_t> tracepoints_;
std::map<std::string, open_probe_t> raw_tracepoints_;
Expand Down