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Documents authored by Raad, Azalea

Document
Invited Talk
DOI: 10.4230/LIPIcs.CONCUR.2024.2
Principles of Persistent Programming (Invited Talk)

Authors: Azalea Raad

Published in: LIPIcs, Volume 311, 35th International Conference on Concurrency Theory (CONCUR 2024)

Abstract
Persistent programming is the art of developing programs that operate on persistent (non-volatile) states that survive program termination, be it planned or abrupt (e.g. due to a power failure). Persistent programming poses several important challenges: 1) persistent systems have complex - and often unspecified - semantics in that operations do not generally persist in their execution order; 2) software bugs in persistent settings can lead to permanent data corruption; and 3) traditional testing techniques are inapplicable in persistent settings. Can formal methods come to the rescue?
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Azalea Raad. Principles of Persistent Programming (Invited Talk). In 35th International Conference on Concurrency Theory (CONCUR 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 311, p. 2:1, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@InProceedings{raad:LIPIcs.CONCUR.2024.2,
  author =	{Raad, Azalea},
  title =	{{Principles of Persistent Programming}},
  booktitle =	{35th International Conference on Concurrency Theory (CONCUR 2024)},
  pages =	{2:1--2:1},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-339-3},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{311},
  editor =	{Majumdar, Rupak and Silva, Alexandra},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2024.2},
  URN =		{urn:nbn:de:0030-drops-207742},
  doi =		{10.4230/LIPIcs.CONCUR.2024.2},
  annote =	{Keywords: Persistent Programming}
}
Document
DOI: 10.4230/DagRep.13.10.50
Formal Methods for Correct Persistent Programming (Dagstuhl Seminar 23412)

Authors: Ori Lahav, Azalea Raad, Joseph Tassarotti, Viktor Vafeiadis, and Anton Podkopaev

Published in: Dagstuhl Reports, Volume 13, Issue 10 (2024)

Abstract
Recently developed non-volatile memory (NVM) devices provide persistency guarantees along with byte-addressable accesses and performance characteristics that are much closer to volatile random-access memory (RAM). However, writing programs that correctly use these devices is challenging, and bugs related to their use can cause permanent data loss in applications. This Dagstuhl Seminar brought together experts in a range of areas related to concurrency and persistent memory to explore and develop formal methods for ensuring the correctness of applications that use persistent memory. Talks and discussions at the seminar highlighted challenges related to correctness criteria for concurrent objects using persistent memory, liveness properties of persistent objects, and how changes in NVM and related technologies should shape the development of formal methods for NVM.
Cite as

Ori Lahav, Azalea Raad, Joseph Tassarotti, Viktor Vafeiadis, and Anton Podkopaev. Formal Methods for Correct Persistent Programming (Dagstuhl Seminar 23412). In Dagstuhl Reports, Volume 13, Issue 10, pp. 50-64, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)

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@Article{lahav_et_al:DagRep.13.10.50,
  author =	{Lahav, Ori and Raad, Azalea and Tassarotti, Joseph and Vafeiadis, Viktor and Podkopaev, Anton},
  title =	{{Formal Methods for Correct Persistent Programming (Dagstuhl Seminar 23412)}},
  pages =	{50--64},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2024},
  volume =	{13},
  number =	{10},
  editor =	{Lahav, Ori and Raad, Azalea and Tassarotti, Joseph and Vafeiadis, Viktor and Podkopaev, Anton},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.13.10.50},
  URN =		{urn:nbn:de:0030-drops-198337},
  doi =		{10.4230/DagRep.13.10.50},
  annote =	{Keywords: concurrency, formal methods, non-volatile-memory, persistency, verification}
}
Document
DOI: 10.4230/LIPIcs.CONCUR.2023.25
A General Approach to Under-Approximate Reasoning About Concurrent Programs

Authors: Azalea Raad, Julien Vanegue, Josh Berdine, and Peter O'Hearn

Published in: LIPIcs, Volume 279, 34th International Conference on Concurrency Theory (CONCUR 2023)

Abstract
There is a large body of work on concurrent reasoning including Rely-Guarantee (RG) and Concurrent Separation Logics. These theories are over-approximate: a proof identifies a superset of program behaviours and thus implies the absence of certain bugs. However, failure to find a proof does not imply their presence (leading to false positives in over-approximate tools). We describe a general theory of under-approximate reasoning for concurrency. Our theory incorporates ideas from Concurrent Incorrectness Separation Logic and RG based on a subset rather than a superset of interleavings. A strong motivation of our work is detecting software exploits; we do this by developing concurrent adversarial separation logic (CASL), and use CASL to detect information disclosure attacks that uncover sensitive data (e.g. passwords) and out-of-bounds attacks that corrupt data. We also illustrate our approach with classic concurrency idioms that go beyond prior under-approximate theories which we believe can inform the design of future concurrent bug detection tools.
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Azalea Raad, Julien Vanegue, Josh Berdine, and Peter O'Hearn. A General Approach to Under-Approximate Reasoning About Concurrent Programs. In 34th International Conference on Concurrency Theory (CONCUR 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 279, pp. 25:1-25:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)

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@InProceedings{raad_et_al:LIPIcs.CONCUR.2023.25,
  author =	{Raad, Azalea and Vanegue, Julien and Berdine, Josh and O'Hearn, Peter},
  title =	{{A General Approach to Under-Approximate Reasoning About Concurrent Programs}},
  booktitle =	{34th International Conference on Concurrency Theory (CONCUR 2023)},
  pages =	{25:1--25:17},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-299-0},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{279},
  editor =	{P\'{e}rez, Guillermo A. and Raskin, Jean-Fran\c{c}ois},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2023.25},
  URN =		{urn:nbn:de:0030-drops-190195},
  doi =		{10.4230/LIPIcs.CONCUR.2023.25},
  annote =	{Keywords: Under-approximate reasoning, incorrectness logic, bug detection, software exploits, separation logic}
}
Document
DOI: 10.4230/DagRep.11.10.94
Foundations of Persistent Programming (Dagstuhl Seminar 21462)

Authors: Hans-J. Boehm, Ori Lahav, and Azalea Raad

Published in: Dagstuhl Reports, Volume 11, Issue 10 (2022)

Abstract
Although early electronic computers commonly had persistent core memory that retained its contents with power off, modern computers generally do not. DRAM loses its contents when power is lost. However, DRAM has been difficult to scale to smaller feature sizes and larger capacities, making it costly to build balanced systems with sufficient amounts of directly accessible memory. Commonly proposed replacements, including Intel’s Optane product, are once again persistent. It is however unclear, and probably unlikely, that the fastest levels of the memory hierarchy will be able to adopt such technology. No such non-volatile (NVM) technology has yet taken over, but there remains a strong economic incentive to move hardware in this direction, and it would be disappointing if we continued to be constrained by the current DRAM scaling. Since current computer systems often invest great effort, in the form of software complexity, power, and computation time, to "persist" data from DRAM by rearranging and copying it to persistent storage, like magnetic disks or flash memory, it is natural and important to ask whether we can leverage persistence of part of primary memory to avoid this overhead. Such efforts are complicated by the fact that real systems are likely to remain only partially persistent; some memory components, like processor caches and device registers. may remain volatile. This seminar focused on various aspects of programming for such persistent memory systems, ranging from programming models for reasoning about and formally verifying programs that leverage persistence, to techniques for converting existing multithreaded programs (particularly, lock-free ones) to corresponding programs that also directly persist their state in NVM. We explored relationships between this problem and prior work on concurrent programming models.
Cite as

Hans-J. Boehm, Ori Lahav, and Azalea Raad. Foundations of Persistent Programming (Dagstuhl Seminar 21462). In Dagstuhl Reports, Volume 11, Issue 10, pp. 94-110, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)

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@Article{boehm_et_al:DagRep.11.10.94,
  author =	{Boehm, Hans-J. and Lahav, Ori and Raad, Azalea},
  title =	{{Foundations of Persistent Programming (Dagstuhl Seminar 21462)}},
  pages =	{94--110},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2022},
  volume =	{11},
  number =	{10},
  editor =	{Boehm, Hans-J. and Lahav, Ori and Raad, Azalea},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/DagRep.11.10.94},
  URN =		{urn:nbn:de:0030-drops-159303},
  doi =		{10.4230/DagRep.11.10.94},
  annote =	{Keywords: concurrency; non-volatile-memory; persistency; semantics; weak memory models}
}
Document
DOI: 10.4230/LIPIcs.ECOOP.2020.21
Data Consistency in Transactional Storage Systems: A Centralised Semantics

Authors: Shale Xiong, Andrea Cerone, Azalea Raad, and Philippa Gardner

Published in: LIPIcs, Volume 166, 34th European Conference on Object-Oriented Programming (ECOOP 2020)

Abstract
We introduce an interleaving operational semantics for describing the client-observable behaviour of atomic transactions on distributed key-value stores. Our semantics builds on abstract states comprising centralised, global key-value stores and partial client views. Using our abstract states, we present operational definitions of well-known consistency models in the literature, and prove them to be equivalent to their existing declarative definitions using abstract executions. We explore two applications of our operational framework: 1) verifying that the COPS replicated database and the Clock-SI partitioned database satisfy their consistency models using trace refinement, and 2) proving invariant properties of client programs.
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Shale Xiong, Andrea Cerone, Azalea Raad, and Philippa Gardner. Data Consistency in Transactional Storage Systems: A Centralised Semantics. In 34th European Conference on Object-Oriented Programming (ECOOP 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 166, pp. 21:1-21:31, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)

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@InProceedings{xiong_et_al:LIPIcs.ECOOP.2020.21,
  author =	{Xiong, Shale and Cerone, Andrea and Raad, Azalea and Gardner, Philippa},
  title =	{{Data Consistency in Transactional Storage Systems: A Centralised Semantics}},
  booktitle =	{34th European Conference on Object-Oriented Programming (ECOOP 2020)},
  pages =	{21:1--21:31},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-154-2},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{166},
  editor =	{Hirschfeld, Robert and Pape, Tobias},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2020.21},
  URN =		{urn:nbn:de:0030-drops-131782},
  doi =		{10.4230/LIPIcs.ECOOP.2020.21},
  annote =	{Keywords: Operational Semantics, Consistency Models, Transactions, Distributed Key-value Stores}
}
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